Nice pictures Mike. I been doing that trick to switches for 25 years. I would like to accentuate the need for touch on this procedure and might suggest the way I have done it. That is with an electrric drill (relatively slow) and an eight inch bit. Use this as a milling bit (come at the work from the side).

The switch holds by the roller rolling over the hill into a valley. The hill wears out and the idea is to undercut the valley. If you do too much the roller WILL NOT come out. Then you have to cut down the hill. There isn't much hill to work with.

BTW, I sure would like to know how to put pictures to this space.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician