I don't know how mechanically inclined you are, but if you are handy and willing to get elbow deep into your machine there are a few things we can try.The oil can get pretty hot, I think the new Holland light comes on at around 150 f.
First off, i'd pull the engine so you can get the pump out. Mark your hoses, drain all the fluid you can and pull it out to dismantle it. The main pump is actually 3 pumps all joinded together, you must keeps the parts for each pump together, never mix them up. The piston pump sections may look the same, but the wear plate is different.
With the pump out, you will want a sheet of glass and wet and dry sand paper. The rotating groups inside the pump run on a brass plate, over time this plate gets a groove in it and looses pressure/flow. If the marks aren't too bad, you can use the glass and sand paper to flatten them again by rubbing them over the sand paper. Just keep turning the plate as to not remove more material from one side. Do the same if there are light marks on the rotating group. give it a good clean and re-assemble with lots of oil.
Next check your vane pump at the front of the piston pumps, look for chatter marks on the outer housing and that the vanes have not worn too thin to fall out of their rotor and get stuck.
After that pull the drive motors down, inspect for wear and replace the Orings.
If you feel you are up for a project like that, let me know and i'll do my best to walk you through the process and diagrams of what you will encounter.
If it takes me a day or two to respond, sorry but i have multiple other projects going on, if you look up my profile and send me an email as a reminder, that will help