Put the on-off switch in place and screw on the original cover to fix the switch in position. Fix the old knob on the new dimmer (needed some glue in ...
I found this beauty in a thrift store. According to the owner it was still in working condition and some of the extra parts came with it (more on the "working condition" later). Nevertheless I decided that it had to be transferred into a dimmable kitchen table lamp.
Step 1: Disassembling and cleaning
Pretty easy: take everything apart, keep the housing, keep ALL the screws, keep the switches and throw away the leftovers. Then give everything a good rinse and rub to get rid of several coatings of kitchen dirt.