I'm in the process of replacing the micro switch for opening the rear hatch window on my E61, following a write-up found elsewhere. However, well into the process I find it's not possible to slide the old switch off the exterior shaft of the wiper spindle assembly: the old switch centre has an aluminium collet that's corroded solid to the shaft (the new switch I've bought is all plastic).

In another thread the poster writes that faced with the same problem he managed to remove the old switch by chiseling away the aluminium collet with a carpenter's chisel.

Question1: any comments to that procedure? Would it be a good idea to try using a fine cutting tool such as a Dremel instead? Or other options maybe? I assume both procedures involve demolishing the old switch entirely.

Q2: The visible part of center shaft has some threads for a fastening nut, but I'm assuming that the threads are only on the tip of the shaft, and not along its entire length? Correct?