So your KB90 locks the portafilter in cleanly again
The KB90 takes the portafilter straight in instead of with the usual twisting motion. That is the whole point of the machine – and it only works as long as the locking mechanism operates without play. This screw is part of it: it belongs to the brass bushing of the locking mechanism and holds it in place.
M4, 12 millimetres long, part number I.1.154. A part you never notice in normal operation that suddenly becomes very important when you dismantle the locking mechanism – because without it nothing fits together.
When it's due
The portafilter has play when locked in, or is harder to slide in than it used to be. During service on the locking mechanism it turns out that the screw head is damaged or the thread no longer tightens cleanly. Or the screw got lost during dismantling – more often than you'd think, because it sits deep inside the group.
At a glance
| Type |
Screw |
| Thread and length |
M4 × 12 mm |
| Location |
Brew group locking mechanism, belonging to the brass bushing |
| Fits |
La Marzocco KB90 |
| Scope of delivery |
One screw |
| Part number |
I.1.154 |
| Installation |
Installation by a specialist recommended |
| Brand |
La Marzocco |
Important for installation
The locking mechanism sits inside the machine at the brew group, right next to hot and pressurised components. Before any work, the machine is disconnected from the mains, depressurised and allowed to cool down. You deliberately won't find step-by-step instructions here: the locking mechanism is what holds the portafilter under pressure, and adjusting it belongs in professional hands.
Who it's for
For service companies overhauling KB90 groups, and for cafés with their own technician who keep a stock of small parts ready for exactly this case. If you're opening the locking mechanism anyway, it makes sense to replace the screw and bushing together.
What goes with it
It goes directly with the brass bushing 8 × 8 × 4,2 mm for the KB90 locking mechanism. If you're taking on the locking mechanism in a bigger way, take a look at the locking hook kit Straight in KB90 and the portafilter holder kit 2.0. All parts for the machine can be found under La Marzocco KB90 spare parts.
Workshop tip from Bern and Zurich
This is our routine, not a manufacturer specification: when a KB90 “clacks” on insertion instead of gripping cleanly, we first check the bushing and hooks for wear and only then the gasket. The fault is almost never where the coffee leaks out. While the group lies open, the machine next to it runs on Very Nutty – strong enough for a long day of servicing. More under Coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold once they have been installed or test-fitted on a machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a quick message and we'll clarify the fit together. Your rights in the event of defective goods remain unaffected.
Frequently asked questions
Is the brass bushing included?
No. What's supplied is the screw. The bushing is a separate item and linked above.
Why does an M4 screw cost so much more than an ordinary one?
Because it isn't an ordinary one. It is part of a precision fit in the locking mechanism and is listed as a separate spare part item – price and availability follow the original, not the standard parts trade.
Can I replace it with a standard M4 × 12 screw?
We advise against it. With a precision fit in a locking mechanism, head shape, tolerance and surface finish determine whether the portafilter sits without play. That's not something you solve from an assortment box.
What material is the screw made of?
We have no verified information on this, so we don't claim anything. It is the original part with the number I.1.154.
Can I pick up the part from your showroom?
Yes. We have two locations: Bern at Gerberngasse 44 and Zurich at Hagenholzstrasse 50b. Drop us a quick message and we'll have it ready for you.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
