Lull 644b hydraulic pump failure

Hi hef looking for some insight. Rear pump section keeps cracking two different pumps appears to be over pressure problem. Inspected relief valve and lowered pressure slowly turned it up until pressure was at 2250 everything worked fine set other relief for front section machine opperated normal . Drove machine 50 feet and pump blew out same extact spot as old one. I can make one pump of the two the housing is the same for front and back g2020 but any ideas what to look for. Plugged return...

Lull 644b hydraulic pump failure

Lull 644b hydraulic pump failure