massey ferguson external forward/reverse hyd pump

I have a chance to buy a old dozer I use to operate many years ago but the owner says it needs a new/rebuild forward/reverse hydraulic pump. It's a external pump on the side of the block(perkins) and he has made a access hole so you can get to it, he also said he had a mechanic look at it and put a gauge on it...... it was toast. I was wondering if anyone has worked on one of these gem's and would help me out with what to expect and if there was a field test to confirm that it's the pump.

Thanks