Hi, it appears it's a common problem with the fiat, also the front scuttle rusts too. I would say in order to do a proper job you would have to take the front screen out and remove the rubber completely otherwise you'll be wasting your time. I believe the windscreen rubber has a retaining bead, once that's removed it allows you to push the screen out . I've done this before on my mini so I think it will be down the same lines,it's not that difficult. This will then give you access to the areas needing repair....