have a 1978 2-105, at 1/3 throttle or less the hydro pressure is weak or nothing at all,  the tractor went through a barn fire, lot of the wire, plastic and rubber was replaced, has a used hydro pump from out mid west, don't know what model it come off of,  is it possible to have internal heat damage ,  worked good chopping 20 acres of corn but chopped 2 loads of haylage and took the pto clutch out, being fixed as we speaks ?  any in sight of what the problem or problems may be