These often have the black plastic General transmission in them. I have seen problems with reverse and other problems. Remove the battery and make sure everything is blown out and free of debris. Same thing with the frame where the drive belt runs. Check condition of belts, pulleys, etc. There is no simple fix I can tell you. These are crappy trans axles that have problems and don’t last as long as the Hydro Gear K46, for example.YTA24V48. Everything with the linkage looks clear. Thanks.