Small Engines (Lawn Mowers, etc.): Mower belt, section splits, riding mower

Question
I have a ceraftsman riding mower with a 42 inch cut.   The belt keeps jumping off the pulleys after just a few minutes.  The belt was put on by sears so I assume it was the right size.  I have to keep putting it back on and don't know if it is the belt or something else.  Thank You

Answer
It's most likely that one of three things is happening.  There is a problem with a guide finger that keeps the belt from popping off if misaligned (normal at different deck heights).  The second issue could be an issue with poor pulley alignment.  The third issue could be related the belt having a problem (frayed section, splits, etc.)  You are going to have to do a thorough visual inspection to determine the problem.  Hope this helps.