I know, old thread but I'm going to add to it anyway
. Here is some more detail (too much maybe) regarding the encoder knob design and its removal/installation. On my Ultra, circa 2011, the knob is a five piece assembly (YOURS MAY BE DIFFERENT): The black knob, the cap on the knob, two brass inserts, and a silver nut. The two brass inserts (one of which is threaded for the silver nut) are internally tapered and fit together such that when the nut is tightened, the internal diameter is reduced causing a clamping force on the encoder shaft. This clamping force is what holds the knob on. The encoder shaft is NOT threaded, it is smooth with a slot on the end. This slot is visible when the cap is first removed, as is the nut and part of the threaded brass insert.
The knob cap was removed with my thumb nail, there is a slightly raised edge, no notch. To remove the knob itself (cap removed), hold the knob with two fingers (you choose) and loosen the nut with a 10mm wrench or socket, just enough for the knob to slip off easily. At this point you can carry out whatever service you intend to do to the unit. When it's time to re-install the knob, and before putting on, snug the silver nut just enough that the brass inserts stop spinning but are still loose enough that the knob slides onto the encoder shaft with minimal effort. At this point you can hold the knob with two fingers and snug the nut with your 10mm wrench. Snug, no need to go muscles nuclear on it. Re-install the cap.
The whole point to this is the fact that, do to its design, this knob could be pried off or pulled off without damage to the encoder depending on how tight the nut was installed initially. I would not recommend doing this. Besides, this is not some cheap little knob, if you do it as stated above you'll be able to see all the neat little design details inside the knob. Fractal owners love the little details, Right?
. Now I'm off to buy some Deoxit.