Clutch stiffness is something which users soon complain about, particulary if there is a loader fitted to the tractor. Some models (eg. MF165) have a grease nipple on the release shaft, which would be the most obvious place to start. However, it is likely that the tractor will need to be split to access the clutch and make further investigations.
The fingers must also be adjusted both correctly and evenly. If the release bearing does not contact all the fingers equally then an uneven release of the clutch mechanism can occur, causing jamming and thus stiffness back at the pedal. Adjustment of each of the fingers can be checked with a simple tool as shown in the diagram.

To: “The Mechanic”,
Cheers, great advice. The clutch pedal is now a lot looser.