I have a gas Ryobi weed wacker. The actual trimmer connection, when snapped into the upper part, does not turn properly. Sometimes the trimmer works...then other times it just slows completely down. It is getting gas, the motor is running fine. It seems that the trimmer connection is not seating properly in the motor part. I thought that perhaps a new trimmer connection would remedy the problem but it has not. The new trimmer head does not spin properly either. Any suggestions?