I need some old pro to tell me what I'm missing. Got a Lull, AKA Prime Mover skid steer with a Sauer-sunderland Series 40 M46 hydrostatic pump system. Has been a great machine. Stopped moving after getting heat temp light on hydraulics. I knew the pump needed overhaul. Sent it to Hydrostatic Trans LLC in Tupelo. They did a full overhaul and returned the unit. Installed and got no pressure to the drive motors. Arms and tilt worked fine. The implement pump was obviously working. But I was getting extreme back pressure into the oil tank. Andy at Hydrostatic said it must be running backwards so I sent it back to Tupelo. Got it back, put it in and got same problem minus the back pressure. I sanitized the hydraulic system and added all new hoses and o-rings. Cleaned tank and installed fresh oil and filter. Gauze metal filter in tank is clean. Pump will not create flow to drive motors. I don't have or even know for sure how to check the charge pressure which is the logical next step. If I can't get this figured out Andy has offered a full refund with the return of the transmission. And I guess I'll part out the rest of the machine. I hate to see it go but I've spent 2k trying to fixit so I got to cut my losses. Anybody got any suggestions.