Used eqpt is ALWAYS a gamble...
Having both pumps recently replaced...there is more than likely some damage to the wheel motors..
Debris from the damaged pumps surely got chewed up by the wheel motors..
Put a magnet in the hydro tank and give it a hard test drive before you hand over the money..
If You Have All The Answers...Except The One You Need...You're Not Trying Hard Enough...
Do The Work