I have taken apart a lot of relays over the years on old cars and fixed them. If you can open the unit up you can usually just clean the contacts with emery or an ignition points file and be good to go. Sometimes you dont get lucky and the contacts are welded or blown clean off if there has been a good short!
These folks make an electronic 4-pin flasher replacement that might be of use.
(in the worst case.) LED adjustable signal flasher
Their units are intended for DeTomaso Panteras, so at least you get to retain some "italian-ness"?