Craftsman tractor, 917.273320, 26 hp Kohler, Is it the ignition switch? Sometimes it works, sometimes just a click, and then I cross it over at the starter with a screwdriver. Starter/sel. Checks OK at local shop. Cleaned all connections at seat/ingition switchs. I can start it without being on the seat. Blade engage switch works with no problem.

This is common on lots of kohlers.
Mine on my Dixe Chopper , did the same.
I went to a John Deere store and brought a hard start relay kit and installed it,Problem solved
Part # AM107421 ,it has instructions its pretty simple to install.