I appreciate all the responses. The obvious problem is the lack of good access to the full lever, and there isn’t a way to keep the mechanism clean.

I’m going to try the Campy shifters. I have a pair of older Daytona, but new silver 10 speed Veloce can be had for $120.

I realize the Veloce is not as nice as Chorus, Record, etc., but when the competition is Claris or Microshift, for about the same price, it is worth seeing if they’ll work with my bum thumb.

Thanks again.

John