I have a Husqvarna 968999220 / CZ4817KOA. At random times while mowing, or even just sitting with the blades engaged, it will throw the deck belt off. It is not a problem to put it back on, however, this will happen on average every 6mins while mowing.

We have taken it in and had the belt and a few pulleys replaced (not sure which ones), but it continues to happen. Any ideas on why this would keep happening?

Diagrams for this model- http://www.partstree.com/parts/?lc=husqvarna&mn=CZ+4817+KOA+(968999220)+(2002-11)

Does it throw the belt off at the bottom of the engine or off one of the deck pulleys?

Does the belt bounce when running,check idlers and tension spring.