Gehl 6635SXT no hydraulics

While moving a light load of dirt, heard a snap/clank, then nothing. No hydraulics to lift/tilt or drive functions. Engine runs, just no hydraulics. It's dead in the field. I'm guessing the gear-pump failed, but only a guess based on reading. Any way to check other then pulling the pump? Any advice on pulling the pump, do I need to drain the hydraulic tank or can I attempt to bag / plug the inlet line to stop flow while replacing the pump? What else could it be if it's not the pump...

Gehl 6635SXT no hydraulics

Gehl 6635SXT no hydraulics