I've got an early 5 speed gearbox with short shift fitted, and it's a bit recalcitrant (is that a word?) when doing what should be the shortest shifts of all 3-4 or 4-3, it's almost like they're not in perfect line any more, I have to hesitate (or it hesitates for me) between shifts.

Is there any adjustment I can make to the cables, maybe there's some wear somewhere?

I'd a problem selecting gear a while ago. If you lift up the gaitor and pull out the soundproofing you will see the stick goes through a white plastic moulded piece which acts as a pivot for the lever. Mine had totally cracked through. when I spoke to two different fiat garages they both said they had sold lots of these parts in the last couple of years as they wear and brake. So I'd check that out first as its so easy to get to

depends on how short the linkage is, I have two now.. One's far too short a I'm now sorting the second one to be a half shift.... Will let you know

I can't find this white plastic thing, have you got a photo or a part number / picture from ePer? Is it right at the base of the gear stick (looks like a metal ball, not plastic?) Reading around, it could be that I need to tighten things up at the gearbox end..?

you can't miss this part. The ball sits into it, it is approx 4 inches by 3 inches rectangular molded plastic. I will try to find an image for you

Fiat Eper moulded gear body Its part number 9 and I also replaced part 22 while I was at it because other forum members also had problems with this bit