Check to ensure that the control is completely set in reverse. Often the shift control may slip or not set completely in the reverse position.
Open the shift casing and inspect the shift fork. The shift fork can get clogged with debris from time to time by mud or rocks. If clogging is evident, clean and grease the shift fork.
Open the hood or chassis and inspect the reverse cable. The cable runs from the engine to the rear axle. If the cable becomes worn or dry, it will not switch the cart into reverse.
Clean the cables and shifter lever free of any visible debris. Spray lubricant on the cables at the rear lever (at the rear end of cable) and on the shifter lever under the hood. Often, poor lubrication is the main cause of the cart not running in reverse.