The flat mushroom head that doesn't stick out at the brew group
A mushroom head screw has a wide, gently domed head with no edges. That is exactly what you need wherever a portafilter swings past or a plate has to sit flush: nothing protrudes, nothing catches, nothing scratches the neighbouring surface. On the KB90 this screw holds the anti-shock plates, and it is also used on the Linea Micra.
This is the original La Marzocco part, M4 with a length of 10 millimetres, part number I.1.099. Anyone who has ever tried to replace it with an ordinary button head screw knows the result: the head is too high and the plate no longer sits cleanly.
When it's due
The slot or internal drive is stripped. The head shows scoring from the portafilter or brown stains. The plate no longer sits flat because the screw has come slightly loose and no longer clamps properly. Or it simply got lost during the last brew group service – that is the most common reason someone reorders it individually.
At a glance
| Type |
Mushroom head screw |
| Thread and length |
M4 × 10 mm |
| Location |
Linea Micra; on the KB90 at the anti-shock plates |
| Fits |
La Marzocco Linea Micra and KB90 |
| What's included |
One screw |
| Part number |
I.1.099 |
| Design |
Mushroom head, gently domed |
| Installation |
Installation by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
The screw sits on the brew group, right next to hot, pressurised components. Before replacing it, the machine is disconnected from the mains, depressurised and allowed to cool down. M4 does not tolerate heavy torque: tighten by hand, not with a cordless screwdriver. We deliberately do not give step-by-step instructions here – anyone working on the brew group should know what they are doing, or call a service technician.
Who it's for
For technicians overhauling a KB90 who want to screw the anti-shock plates back on properly, and for Micra owners who lost a screw during servicing. Also worth keeping in stock – it is small, inexpensive and never there when you need it.
What goes with it
Directly related are the sleeve for the anti-shock plate screw KB90 and the brew head gasket including two anti-shock plates KB90. You'll find more parts in the categories La Marzocco KB90 spare parts and La Marzocco Linea Micra spare parts, and all together under Original spare parts.
Workshop tip from Bern and Zurich
This is our routine, not a manufacturer specification: before screwing the anti-shock plates back on, we wipe the contact surface with a damp cloth. Coffee grounds under the plate feel like a crooked screw when you tighten it – and then it's easy to overtighten. The pot next to it is usually Nutty Delight or Very Nutty; everything else 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 after installation or a test fit on the machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a line and we'll clarify the fit together. Your rights in the event of defective goods remain unaffected.
Frequently asked questions
Is this the same screw as the M4 × 10 for the Linea Mini front?
The manufacturer's list gives the number I.1.099 for both positions, but the head is different: this one has a mushroom head, the front screw of the Linea Mini a slot. That's why we list them as two items. If you're unsure which one you need, send us the serial number.
How many screws do I need for the anti-shock plates?
That depends on the number of groups on your KB90 and is stated in the service documentation. The list doesn't give us a quantity, so we don't claim one here – best count them on the machine or ask us.
Is the sleeve included?
No. The sleeve is a separate item and is ordered separately. It is linked above under “What goes with it”.
What material is the screw made of?
We have no verified information on this, so we make no claims. It is the original La Marzocco part with the number I.1.099.
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 line 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.
