Had a 99 loral floater air fert spreader that was having trouble with the EZ-steer. The truck turned hard didn't want to follow the line and would kick out the manual override.   I put a ez-pilot on it and it was better but not 100% finally the steering sector went out and I put a new steering sector on it and wow steered like a dream and the ez-pilot worked great. So I guess I would make sure your steering sector and everything is good before you so anything. If you cant turn the steering wheel when standing still you probably got a problem with the sector of the pump.