Moinmoin,
there s a second possibility, which I applied when our Trumpet-player hit the very important "Param1" knob :-(
The knobs themselves sit on the axle of the pots / encoders (of course). These axles themselves however are - at least in my case - not massive, but feature a hollow shaft. Its diameter is not perfectly round, but has a flat side.
- So first try to get the knob itself from the rest of the broken shaft still sitting in it.
- If You can - or know somebody who does, like e.g. a hobby builder of model cars - try to make a piece of plastics, that fits into the hollow space of the pot / encoder and links it to the broken part.
- If You manage a tight fit, You will not even need cement to fix the pot's / encoder's axle.
- Then simply put the knob itself at its place again.
Still works for me, after a while the knob felt a little bitt sloppyer than its siblings, which was cured by carefully applying a bit of cement (not at the knob, but within the axle)
HTH
Martin