I think you have a problem with the linkage adjustment. If your servo is working correctly and you have reverse, then most likely, it's all in the linkage. My advise.... Start the engine without the Radio on. Be careful and hold the carb with you fingers and manually push and pull on the tranny linkage. You'll probably find the tranny to jump foward. If this is so, then it is definitely a linkage prob. If not use El's idea and rip apart the tranny..