Unit has 2600 hours on it done routine maintenance oil,filters , brakes. Today after never having a problem Ann’s hadn’t driven for a couple weeks. Took off after a brief warm up was @45* noticed motor turning up more then usual in flat ground only running 20 mph went down hill and noticed it was freewheeeling down not engine braking , turn around tried to come back up hill motor reved but not wanting to pull. Smelt a slight burn smell but no noise. Parked it didn’t attempt to go up hill again. No leaks or unusual noises.