Master cylinders for both the brakes and clutch. They cost 70 Eur a piece, when bought from the dealer you get OEM Fragokov cylinders which are tons better than the PAL ones as factory fit in the early years.
The water pump needs to be looked after, it will cost you about 120 Euro for a new one.
The gear selector/shifting mechanism fails sometimes, causing you to engages two gears at the same time, causing the gearbox to stick. You release it by a pin on top of the tranny, no big deal just 10 minutes of work.
To prevent this, there is a 15 Euro factory mofification kit that installs in an hour of work.
Also the
fuel feed pump leaks sometimes.
There are some weaknesses on the 80's models, that last not as long as the rest of the tractor, but they are pretty cheap to fix.
They are just good tractors, but you have to check these mentioned things.