Small Engines (Lawn Mowers, etc.): Craftsman mower drive belt slipping, craftsman lawn tractor, transmission pulley

Question
my craftsman lawn tractor mower's drive belt is getting caught under the transmission pulley.  I freed it, put it back together, ran it, and things looked good, until i stopped and engaged the brake.  when I started again, the belt had slipped and was caught again under the pulley.  It seems that the belt is very lose when the brake is engaged.  Craftsman model 917, 19.5 hp, 42" cut automatic lawn tractor.  Thanks.  Jesse Ortiz

Answer
Have you recently replaced the belt?  This is the first thing we do when we have a belt that continues to slip off.


There should be a tension ajdust on the idler pulley.  The idler pulley is connected to the clutch pedal.  Usually loosening the idler pulley nut allows you to slide the pulley to tension the belt.
Let me know about the belt.
Eric