Small Engines (Lawn Mowers, etc.): Toro Lawn Mower, crankshaft pulley, transmission pulley

Question
My husband has a Toro Lawn Mower that is only 3 years old and recently has developed a problem with throwing the belt.  He is usually very skilled in fixing the problems but this has him stumped.  He has check the pulleys and the blade shafts and all appear to be okay.  Any Ideas?

Answer
Usually when a belt is thrown it breaks the cords in the belt.  You would have to replace it.  The other thing to check is the belt guide(s).  They hold the belt on and wrap part way around the transmission pulley and the crankshaft pulley.  The have to be in place and with-in 1/8th " of the pulley.  

If only 3 years old the design is that the transmission rocks backwards to tighten the belt and drive the mower.  If it comes off when the transmission rocks forward be sure it is not rocking to far.  There is downloadable manuals at www.toro.com under customer care.  It will take a few clicks but you can get to it as long as you have your model and serial number. Hope I helped.