hydrostatic trans

If it's hydrostatic, there are no external adjustments. First possibility would be possibly low on oil, after that it's basically seals/weak pump kind of things.

If it's slipping, it's just about ready to quit altogether. No matter the reason WHY it's slipping, the damage that's causing it to slip is permanent and fatal. Time for a new machine...

Actually, I'll modify that slightly -- it's possible there's a linkage problem and you're not getting full open to the control valve(s). That did occur on my 955 utility tractor. But, of course, that's not slippage in the transmission, it's an external controls problem.

I wouldn't go so far as the other poster as to say there's no h