Gear box is out and opened up. Don't even consider doing this without the amazing thread from
Mr Wild.
https://www.fiatforum.com/punto-ii/158346-input-shaft-bearing-renewal.html
You will need some Loctite 518 anaerobic gasket sealant, moly grease for the new seal, PTFE tape to protect the splines and two small zip ties to retain the reverse selector bracket bolts. Magnetic prod to extract any bolts that drop into the gearbox.
The reverse gear selector mechanism prevents the bell-housing/front coming off the gearbox. I imagine the factory fits this end first. Mr Wild explains it well... After unbolting the casing, open it about 20mm and remove the two M8 bolts holding the selector bracket to the end cover. You can now extract the cover from gearbox.
The six speed box input shaft has a no cage roller bearing fully packed with rollers. I have not replaced mine. The oil seal is fitted from inside the cover. Get the correct part from Shop-4-Parts. Mine was age-hardened and not doing anything close to what a seal should do.
I knocked the old seal out using an old flat screwdriver bent at the end like a mini pry bar. The seal popped out easily no need for self tapping screws. New seal was fitted with a suitable socket as a drift. I greased it internally with moly grease. To protect the seal, I wrapped the clutch splines with PTFE tape working out from the bearing end. It's better than PVC tape as you can wrap all the way down and not worry about some of it getting left around the shaft.
You will need a helper to refit the bell-housing end cover to the main gearbox.
(1) Put the two bolts through the reverse gear selector bracket and put a small zip tie around the bolt threads. This stops them failing into the gearbox.
(2) Smear the joint face with Loctite 518 anaerobic sealant.
(3) Slide the cover onto the box. You have to align both bearings so help is needed. When the bolt line up, get them started and align the reverse gear ball joint as you go.
(4) You now need a helper to make sure the selector stays in place while you tighten the two bolts.
(5) Slide the cover fully into place. I used two bolts from the selector cover to pull it on. They are a little longer so the threads don't get stressed. Check the reverse gear selector works then fit the correct bolts and fully tighten them all.
(6) Test fit the shifter cover to make sure the gear selectors are lined up properly. If the top arm flaps about you need to try again.
(7) When you are happy, smear the joint face with 518 and fit the shifter cover. It has four longer M8 bolts plus one that has a stud attached.
(8) Remove the PTFE tape from the input shaft splines. It's self lubricating so no worries if a little tape gets left under the release bearing sleeve.
Job done, Now time to put the box back into the car.
It's clear the input shaft seal can hardly outlast the clutch. Fiat improved the bearing over older models (its a close set roller bearing) but they should have made it possible to replace the seal from the outside. The fix was a poor effort from Fiat. My bell-housing is surprisingly clean inside but the clutch is *ked with oil.