MF20 front hydraulic pump

The pump had been in service for a few years (I don't know what happened to the original pump), and I got an AGCO replacement from the dealer. It was in light duty service for about a month and the pump body cracked in the same place. Does anyone know if this is a problem with re-manufactured parts or is there something in the hydraulic system that I need to look at?

Dealing with the hydraulics is a new thing for me. When I mounted the new pump I aligned everything carefully, use a torque wrench and went by the specs. Before I spend a grand on another pump I wanted to try and find out if there is something I am overlooking.

A bit of history: we were using the tractor to transport supplies and tools to the pump house to pull and replace the pump for our fishing ponds. At the end of the day, when we got ready to leave, the wheels spun in leaves and sand, and the tractor slid off the roadway at the pump house. We unloaded the bucket and I was using the loader to push the tractor back onto the road and the hydraulics just stopped responding. I unbolted the bucket, got the unit back to the shop and tested the flow from the pump. Low flow (>4 gpm). SO I pulled the pump and found that the key had rolled in the shaft. Put in a new key, was priming the pump at low RPM and the casting broke. Then I put on the new pump and the same thing happened after being in service for a few weeks.

The front end seems to be okay.

This has been a one owner tractor and only works an hour or two a day during the summer except on mowing days, then it might put in 8 hours pulling a finish mower. Flat ground and gravel roadways.

When I pulled the pump to replace it with the new one I noticed that the new key had some twist to it. I'm anxious to see if the key that came with the replacement pump has some twist or shear to it.

I'm beginning to think that reason that the key spun and ground was in response to a blockage or failure in the main valve and that instead of cracking the pump, the key failed.

I'd like to take it to the shop, but last time there was a problem with the hydraulics, they kept it for over two months, charged $2500, and when it came back, the bolts for the hood and radiator shroud were missing so that the sheet metal was banging against the pump every time you hit a bump.