Recently lost ground belt on Z248f mower. Belt replaced but now mower has a hard time moving. A little better in reverse but not much. No noticeable problem before belt was lost. Belt is tight and is not slipping on drive pulley. Are there any adjustments I am missing? Hope to hear from some of you experts on hydraulic motors. There is a video on you tube on repairing these unites but may be a bit much for my 84yo eye. pt# 510 37 56-01 and 510 37 56-02 , right and left. Made by Hydro Gear.