How to Replace Coffee Machine Group Head Seals and Shower Screens

Last updated: August 2026

In 30 seconds:

• The group head seal is the rubber ring inside the group. It squeezes against the portafilter and stops water escaping while the shot runs.
• The shower screen is the perforated disc above it. It spreads water evenly across the coffee bed.
• Change both together. The parts cost very little next to the mess and the lost service a worn group causes.
• Expect 6 to 12 months on a busy bar, and longer on a quiet counter. Judge by feel, not by the calendar.
• The job takes about 30 minutes per group with a screwdriver and a seal pick. On most machines you will not need an engineer.

Not sure the seal is your problem yet? Work through our guide to coffee machine leaks and group head drips first. It separates seal wear from the six other things that put water on your counter.

What the seal actually does. Espresso is brewed under real pressure. The seal is the only thing holding that pressure inside the group while the portafilter is locked in. When the rubber hardens, the joint stops sealing and water takes the easy way out, which is sideways past the handle.

Why a tired seal costs you money. A hissing, spitting group is not just untidy. Pressure that escapes at the edge is pressure that never reached the coffee, so shots run fast and taste thin. You throw drinks away and slow the queue down.

Why the shower screen goes with it. The screen sits directly above the seal and blocks with old coffee oils and fine grounds. A blocked screen pushes water down one side of the basket, which is called channelling. Once you have the group apart, changing the screen adds about two minutes.

Here is the honest summary. The biggest mistake we see is cranking the portafilter handle further round to stop a drip. That does nothing for hardened rubber. It wears the lugs on the group and the ears on the portafilter, and that is a workshop repair rather than a five pound part.

Signs your group head seal is finished

Most seals give you plenty of warning. Look for these.

What you see	What it usually means
Water squirts or hisses out at the side during a shot	Classic hardened seal. Replace it.
The handle has crept past the centre point over the months	The rubber has compressed. Replace it.
The seal feels hard and shiny to a fingernail	Replace it. Good rubber is soft and springs back.
You have to force the handle to lock in	Coffee grounds baked into the seal channel. Clean, then judge.
Shots run fast and taste weak on one group only	Pressure loss at the seal, or a blocked screen above it.
Water runs down the outside of the portafilter spout	Screen or seal. Strip the group and look.

One quick test settles it. With a clean, empty portafilter, lock the handle in and watch where it stops. A fresh seal usually stops the handle short of the centre line. A handle that swings well past centre is sitting on rubber that has given up.

What you will need

• A group head seal to suit your machine, and a shower screen to match.
• A flat screwdriver, plus a cross head screwdriver for screens that are held by a centre screw.
• A seal pick, or a small sharp hook. A thin screwdriver will do if you are careful with the group face.
• A group head brush and a clean cloth.
• Food safe grease is optional. Many engineers fit seals dry, and a smear of water is usually enough.
• Gloves. The group stays warm for a long time after switch off.

Buy spares before you strip anything. A group in pieces at half past seven in the morning is not a good place to start a parts hunt.

How to replace a group head seal and shower screen

Allow about 30 minutes for the first group. The second one takes half that.

Step 1: Switch off and let the group cool

Turn the machine off at the switch and at the socket. Leave it for at least 30 minutes. The group is a solid lump of brass and it holds heat far longer than the body panels suggest.

Step 2: Remove the portafilter and clean the group face

Take the handle out and set it aside. Brush the underside of the group until you can see the edge of the screen and the rim of the seal clearly. Working blind is how group faces get scratched.

Step 3: Take out the shower screen

Some screens are held by a single central screw. Others are a push fit held by the seal itself. Undo the screw if there is one, then ease the screen down and out. Keep the screw somewhere safe, because it is small and it loves drains.

Step 4: Prise out the old seal

Push the pick into the face of the old rubber, not into the gap behind it, then lever downwards. Old seals often come out in pieces, which is normal. Do not gouge the metal channel above it.

Step 5: Clean the seal channel

Scrub the empty channel with the brush and wipe it dry. Any grounds left behind will hold the new seal proud and it will leak on day one. This is the step people skip.

Step 6: Fit the new seal, then the new screen

Offer the seal up square. If it has a bevel, the narrow edge normally faces up into the group. Work it in a little at a time all the way round with your thumbs. Then push the screen up under it and refit the screw.

Step 7: Test, then check again after service

Power up, let the machine come back to temperature and run water through the empty group. Lock a blank portafilter in and run a short shot. Then check the group again at the end of your first busy service, because a new seal beds in.

Getting the right size seal

This is where most orders go wrong. Seals vary by make, by group design and sometimes by build year. A part that fits one two group machine will not always fit another.

• Do not order from a photo. Two seals can look identical and differ by half a millimetre in thickness.
• Keep the old one. Measure the outside diameter, the inside diameter and the thickness, and note whether the profile is flat or tapered.
• Quote the model and serial number. They are on the plate at the back or under the drip tray, and they settle the question in one email.
• Check your own model manual first. It is the only source that is right for your exact machine, and we will not guess a size for you.

Where to get seals and screens

Being straight with you: we do not list individual group head seals and shower screens on the site. They are model specific, and a page of near identical rubber rings would send more people to the wrong part than the right one.

Send us your model and serial number and we will sort the correct parts through the supplier. Come to us rather than the manufacturer, because we handle the trade channel for the machines we sell.

When to stop and send the machine in

Seals and screens are routine consumables. Some faults behind them are not.

• The group still leaks with a new seal fitted correctly. The face or the channel may be damaged.
• The portafilter lugs are visibly worn or rounded off.
• Water is coming from behind the group rather than from the joint.
• The machine will not hold pressure. Our guide to reading a coffee machine pressure gauge will tell you whether that is what you are looking at.

Warranty work on small and medium machines is back to base, at the supplier workshop. There are no engineer site visits. Collection is your cost, at roughly £95 to collect and £115 to return, so about £210 for the round trip. Drop the machine at the workshop yourself and you avoid the collection fee. Our page on coffee machine servicing and warranty sets out how that works before you need it.

How to make the next seal last longer

Seals die of heat, pressure and baked on coffee oil. You cannot do much about the first two.

• Backflush every group at close down, and use detergent on the weekly clean. Our coffee machine cleaning and descaling routine covers the schedule.
• Brush the group face and under the screen daily. Thirty seconds a day roughly doubles what you get out of a screen.
• Do not leave the portafilter locked in overnight. Constant clamping pressure on hot rubber flattens it early.
• Keep your water right. Scale hardens seals and blocks screens, so a water filter or softener changed on time pays for itself.

Five mistakes that turn a cheap job into an expensive one

1. Tightening the handle harder instead of changing the seal. You wear the group lugs, and those are not a consumable.
2. Levering with a screwdriver against the group face. A scratched face will leak with any seal you fit.
3. Fitting a new seal onto a dirty channel. It will sit proud and drip from the first service.
4. Reusing a blocked screen. The new seal gets blamed for uneven shots that are nothing to do with it.
5. Working on a hot group. Burns are the obvious risk, and warm rubber tears rather than lifts out cleanly.

When it is the machine, not the seal

If you are fitting seals every couple of months, or paying for repeat workshop visits on a machine that is already old, the sums change. A single group machine such as the Fracino Cherub starts from £1,240, and it is tank fed, so no plumbing is needed.

Quick specs, Fracino Cherub CHE1

• 1 group, tank fed with a 3 litre tank
• 2.3 litre boiler, 2.85kW element on a standard 13A socket
• 18kg, so it moves without a trolley
• From £1,240

Best for a small counter or a second service point where volume is modest and plumbing is awkward.

Busier sites outgrow one group quickly. The Bambino 2 Group Automatic starts from £2,380.

Quick specs, Bambino 2 Group Automatic BAM2E-3V-IVORI

• 2 groups, plumbed in, 10 litre boiler
• Up to 400 cups per hour in automatic form
• 2.85kW on 13A, 535 x 580 x 500mm, 55kg
• From £2,380

Do not buy it for a site with no cold feed and no drain within a metre, because plumb in machines need both.

Trade-off. Two groups double your peak output, but they also double the seals and screens you look after. That is a fair swap when the queue justifies it.

Frequently asked questions

How often should a coffee machine group head seal be replaced?

Every 6 to 12 months on a busy bar, and longer on a quiet counter. Volume, water hardness and your cleaning routine all move the interval. Press the rubber with a fingernail: soft and springy is fine, hard and shiny means it is finished.

Can I replace a group head seal myself?

On most commercial machines, yes. It needs a screwdriver, a seal pick and about 30 minutes with the machine switched off and cold. If the leak continues once a correctly sized seal is fitted, stop there and have it looked at.

What happens if I ignore a worn group head seal?

You lose brew pressure at the joint, so shots run fast and taste thin. Staff compensate by forcing the handle further round, which wears the group lugs and the portafilter ears. A part worth a few pounds becomes a workshop job.

Should I replace the shower screen at the same time?

Yes, in almost every case. The group is already apart, the screen costs little and a blocked screen will make a brand new seal look like it has failed. Fitting them as a pair also gives you one date to remember.

How do I know what size group head seal to order?

Do not guess from a photo. Measure the old seal, note the profile, and quote your machine model and serial number, which are on the plate at the back or under the drip tray. Your own model manual is the definitive source.

Does changing a seal myself affect the warranty?

Seals and screens are consumables and are not covered by warranty in the way a boiler or a pump is. If your machine is still in its warranty period and you are unsure, ask us before you strip the group. Warranty repairs are back to base at the workshop, not on site.

Why does the portafilter stop before centre after a new seal?

That is correct and it is a good sign. Fresh rubber is thicker, so the handle locks up earlier in the turn. It will settle a little further round over the first few weeks as the seal beds in.

How long does the job take?

Around 30 minutes for the first group, including cooling time you should not rush, and roughly half that for each group after it. Do it after close rather than before opening, so a stuck screw is not an emergency.