Hi, I seen these tractors pull for a number of years and they will pull well.
The weight classes that I seen them pull in was 800-1200# class this is tractor and driver
combined weight and this was in Stock and Prostock classes, sounds like you need to do some belt work
to keep it from slipping I,ve use belt dressing in some cases but it could be a wrong belt or clutch
mech. that could be causing this. Put it this way I never seen one totaly break down in the classes I mentioned.
chuckm