I traded a small utility trailer for a 1969 mtd 1500 series 46"cut. It cuts great and starts every time, but lately i been having problems with the transmisssion. It's pto drive to the blades. When i engage the blades and run for awhile it won't stop no brakes , push in the clutch and nothing i have to turn the key off to stop it. Then when i put it in gear it won"t move unless i rock it. please help.