One of the hydraulic pumps sounds very bad. in one direction everything is o.k. and sounds good but in the other direction it sounds very bad. How could this be is there a eletric propblem with the field? or if it works in one direction fine than the field must be o.k.? any thoughts would be helpfull

How old is the pump? The brushes may be going bad. All the motor does is spin two gears.

This is the old style Pump i think it's called prestolite type. the type with the not translucent reservoir. i opened it and the brushes seems to be ok. a friend told me this is low oil can it be?
Thx