When the car is cold the gearbox works fine , but when she warms up the selection of gears becomes very stiff to engage , any idea what causes this and how to fix please .

Alan .

Check the oil level (especially if 899 or 1108 S or SX). Most likely, though, the clurch cable just needs adjusting.

Lots of threads on this -- try turning the nut 2 clicks clockwise.

Thanks , can you tell me how to check the oil for the box please .

Alan .

if you have wet inner drive shaft gaitors and they have oil drips on them you need to add more oil and replace the gaitors

the oil filler plug is on the front face of either box it will need a key to undo the oil may flow out or you need to stick in a small finger or similar if the finger comes out clean the box is low in oil.

you fill to spill out

if the gaiters have leaked take bus to factors don't drive

FIAT specify a full synthetic which is £ but it is ok for 72k miles if previous owner may have put in lower specification oil that may be part of your problem

The boxes are not wonderful in good condition with the full synthetic