my four wheeler was running fine until i got the idea to use to to pull a 1000 lbs tractor back into the barn. other then riding the clutch i didn’t think i was doing any harm. However now it shifts through all 5 gears but doesn’t accelerate at all. in 5th gear its going about as fast as it should in 1st. it reminds me of a vehicle with a clogged catalytic converter. any suggestions on repairs??