Sorry to hear about the problems-------doesn't make much sense, does it?????

It sure sounds like a strange carb problem of some sort, since the mechanical parts of the engine do not (and can not) change.

If something was clogged up in the crankcase pressure line going into the carb base (dirt, gunked up castor oil, etc.) it could cause carburetion problems, since the pump diaphram wouldn't work correctly. You could try running a thin wire through the passage way, to clean it out (maybe some disassembly will be required).

Did you have any luck trying to get ahold of Tillotson??????

Regards, Dave