Scotts 16 H lawn tractor - motor runs fine - belts are good - problem is I have no power in forward or reverse. Transmission seems like it's slipping. I want to know if there is way to put transmission fluid in. It acts like it is low. I can't figure where to check to see if fluid is low or if that is even what is wrong. Does anyone have any idea what the problem might be. This lawn mower is about 6 yrs old.