I've got a Craftsman mower (917.372852, roughly ten years old or more)) that worked fine until one day last week when cutting heavy, wet grass. Since then, the self-propelled mechanism has little power. It'll work on a bare surface but gives up whenever there's any resistance. So the behavior is like night-and-day, from before that one day.
I took the top cover off and can see that the belt looks okay and the inside area is *not* all clogged with debris. However, I cannot see where the belt wraps the pulley underneath the engine, on the main shaft. That part has a heavy cover underneath, that prevents access but also presumably prevents grass from getting up in there.
Drying for a week didn't help.
What should I check next? What part would be slipping?
Thanks.