You must be the telephone man – suspect you’ve heard that one before.
Well, you probably have either worn wiper sockets (plastic/nylon ring around the wiper shafts – they can be bought separately using a Fiat Tipo part No.). I’ve got the No. somewhere, mail me if you need it. Or you need to fine a just the arms a bit more – it a very delicate matter, I’ve had to do it several times, myself.
If you have the jerkily action on the parking stoke you’ll find the cure looking up one of the earliest entries of the Technical Forum.