I have a two year old Sears Craftsman lawn tractor with the 42" mowing deck. It works well with one annoying exception. Almost every time I want to mow, the drive belt has slipped off of the power take off pulley and is hanging slightly below it. I have to get off the tractor and reach underneath to fit the belt back on the pulley. The belt is properly set in that little J-hook guide thing hanging down on the right side of the PTO pulley. Sometimes it takes two or three attempts because the belt falls off when I start the tractor.
Once it engages, it's fine. No slippage, cuts the grass without problems. I can stop the tractor, disengage the mower drive, and restart with no more problems. I've replaced the belt with the size recommended in the user manual but the same thing happens.
Any ideas of why this would be happening?