Well I'd check to be sure all gear boxes are full of oil. See if there are leaks. Check my other post on here on the MFWD I made where I fixed a vertical axle and replaced the seal and o rings. Here is the video Over all in 21 years I've had mine other than that axle issue I haven't had any MFWD issues other then I replaced the rubber o rings now on both sides. Mine gets used regularly here on the farm. Its not my main tractor however its my only loader tractor and its used for many jobs around the farm. The old blue MTZ82 tractor in the video below has LOTS of hrs on. On this side of the pond what I've seen give troubles often are the o ring and seal. They can leak external (o-ring) or internally (internal seal). When they leak internal the top angle gear box leaks into the bottom and you don't notice. When it runs dry of coùrse it wrecks the angle gears. You have to keep an eye on these oil levels. 825/925's are getting harder tó find now a days. Years ago you could pick them up for a bargain often. Many old used ones have been exported outside the country for other markets. But they are around if you have patience and really are the best bang for Your buck on a 80-95hp MFWD tractor. You will find many tend to be beat up and uncared for unfortunately. Find one with a loader joy stick & valves on it as the factory remote levers are awkward for loader work and in general. They may not me the most comfy tractor vs other brands the same age but they are the simplest and most economical to fix/maintain. You don't want to know what it costs for parts if you take out a wheel planetary gear set on a MFWD on other brands. Wouldn't hurt to lift up front end and check wheel bearings. Here is a video on that.