Are you using genuine belts?
If you are fitting replacement/pattern belts of the same size they are not always re-inforced in the same way a the OEM/genuine part. Problems especialy occur when (on some cutting sytems) you have a twist in the belt or pulleys running on back of belt.
I would also give your deck a good checking over to ensure that pulleys are all aligned and they have no signs of damage or wear (chips, burrs or gouges/grooves). Also check all deck bearings for play or tightness especialy in idlers.
I hope this helps.
Robin S, September 2008
