All i see wrong in the cab is the crappy Deere upholstry that has all fell apart and a few knobs missing.  We've had the headliners fall down at 2000 hours on later model tractors.  Even AGCO only charges $20 for a knob...it might not fit when you get it, but you know...I don't know what the upholstry will cost but I am betting Fehr has it and it's not  much over $500. 

Those belts will run fine as long as you arent doing something in the mud.  A slick will even pull better then one with new grousers on hard ground. The midwheels and drivers 

What do you expect from a tractor that is 12 years old with fifteen thousand hours on it?