I have a 1981 B7100 and the 3pt hitch will not raise or lower, also have a front snowblower and that valve does not move in or out either. the control valve under/front of the seat is in the correct position (tried moving it and still did not work). changed fluid and checked filters and they were clean. the 3pt control valve when moved does not pop back to neutral. Does anybody have any ideas i can try?