Remove and replace cycle select knob

knob looks like this (actually it's the new one which is a little different than the old one). The cover can be gently levered off- I think I used my thumbnail. Knob now reveals a number of slots, the 3 larger ones allow access to the lugs that hold the knob on

This is the centre of the knob after drilled apart for removal, showing the lugs that click into place and which probably can be bent inwards by using a special tool via the slots shown in step 1. I tried mini screwdrivers, but with no success.

By carefully drilling two sets of holes with a small drill bit, and then using a larger bit to join the holes I was able to remove the outer part of the knob, then the inner piece, containing the lugs. The part of the knob that sat over the metal shaft had just broken. Replacement knob reinforced with metal clip. Clicks into place.