Well that's that! After 7 months of throwing money at my 156, I've cut my losses and got rid of it. In that time, it never managed a full month without a trip to a garage, mainly to try and sort selespeed leakage. Belts done, brakes done, full service & MOT'd and finally no leakage from the selespeed, I've traded it in against a new Fiat 1.2 sport.
Thanks to Mike at Robert's Aerospace for sorting the leak, and the rest of the work done on the car at a very reasonable cost. Difficult to get to, but worth the effort.
Good luck to whomever ends up with it.... it has been fault free (execpt for flashing 3rd & 5th digits, which we never managed to cure) for the last week. I didn't dare mention that it was going in case it threw a wobbly.