The pin that holds the knob on its spindle
A rotary knob does not simply sit on its spindle, it is secured. On the RE A, this pin does the job: a small pin that positively locks knob and spindle together, so the turning motion is transmitted and the knob cannot be pulled off.
Because it has no sealing function and is never under pressure, it is often overlooked – until it is missing. Then the knob spins freely without the tap responding, and suspicion wrongly falls on the valve first.
When it is due
The knob turns, but nothing happens: no steam, no water, no noticeable resistance. That is the classic sign of a missing or broken pin.
A second sign is play: the knob wobbles on the spindle, or it can be pulled off a little. In that case the pin is still in place but worn out.
Sometimes the pin turns up in the drip tray. Refitting it bent is not worth it – it rarely lasts long after that.
At a glance
| Type |
Retaining pin |
| Fitting location |
Steam and water knob, connection to the spindle |
| Fits |
Rocket RE A |
| Scope of delivery |
one pin, without knob and without spindle |
| Part number |
R999904985 |
| Material |
Metal |
| Brand |
Rocket |
Who it is for
For businesses with an RE A whose steam knob spins freely or has play.
For workshops that are removing a knob and want to replace the pin during reassembly. The RE A is not a permitted model value in our category system – the item can be found via its title, number and the Rocket category.
What goes with it
The same tap also has the O-ring for the steam and water tap and the spring.
We stock the knobs and caps individually, such as the Cellini and Giotto rotary knob and the rotary knob cap without logo.
For an overview, see Rocket accessories and spare parts and Original spare parts.
Our trick when fitting it: we place a flat tray under the work area before positioning a pin. Small parts that fall into a commercial machine usually only reappear at the next service – and until then they rattle. This is our habit from Bern and Zurich, not a manufacturer requirement. Once the knob is back on, we steam some milk and pull a cappuccino with Nutty Delight.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold once fitted 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 line and we will check the fit together. Your rights in the case of defective goods remain unaffected.
Frequently asked questions
My steam knob spins freely – is it always the pin?
Not always, but often. It can also be the spindle or the valve. The pin is the cheapest option and therefore the first thing to check.
What are the pin's dimensions?
No dimensions are documented for this item. The binding reference is the number R999904985.
Does it also fit other Rocket models?
The documentation lists it for the RE A. For other series, we are happy to check the fit using the serial number.
Can I fit it myself?
The pin sits on the outside of the knob, so there is no need to open the machine. With a little patience and the right pin punch, it is doable.
Can I see the part at your showroom?
Yes. We are in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Bring the removed part with you, we will compare it with the replacement on site and you only take home what really fits.
Questions about fit or your machine's serial number? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
