The failure was in the pressed paper board that holds the contacts that the slider engages when pulled back and forth.
It seems that is a common failure point, the glued paper board is pushed against by 2 strong springs all the time and it starts flexing away from the contacts.
I made a new board by JB Epoxy welding 5 layers of Formica counter top together into a strong square block. I sanded the boards to get a better surface for the epoxy. Drilled 2 holes and used small brass screws and nuts for the wire connector. I also flattened down the bolt heads and filled the Philips screw slot with some plumbing solder. I then countersunk so the head was more flat with the board (on the inside). That lets the sliding contacts move easily into place.

The question of holding the Formica board to the switch housing was an unknown, but motor winding wire worked fine to do that. I thought about buying new, but this was cheaper and the switch is really very good quality.
If you straighten out the paper board crimps upright slowly and carefully, they wont crack off, and they align the new board in the proper place.

I think the Formica is more durable paper board than what ever they originally used. With all the the extra thickness, it is certainly a lot stronger.

 

An even better material would be glass fiber circuit board material,which does not soften with reasonable heat, and is stiff enough to work with just one layer.