[Ron Ramirez]

Also note that if a carbon track has burned into the phenolic of the band switch (which is very likely your problem in this instance), that carbon must be removed. That may include digging into the phenolic. You will have to operate very carefully to keep from breaking the phenolic if you have to scrape the carbon out. Fill the resulting groove with epoxy after making sure all carbon is gone. Been there, done that, and have another such problem switch waiting for me - a 37-650.