rancher autodrive ( model 28151/180 serial 3807164 ) trouble getting it to drive, needs lots of pressure on pedal. has had new friction corks fitted about 3 moths ago ( stil look in good condition ) and was adjust to go both forward and reverse but it needed a bit of pressure to make it go froward. we adjust it to go forward with only a fair pressure it will not go back. if we adjust it to be midway it will go both forward and reverse but requires a lot of pressure on pedal to go. brake is off .