Have a look on the www.gomog.com website - technical manual section - the wiring diagram for your car is there (only RHD though). It sounds almost certain to be a fuse or simple broken connection. Any competent motor electrician should be able to fix it, you shouldn't need a dealer.

Or you could try contacting someone via the Morgan Club of Italy
www.morganclubitalia.it

There may well be someone near you who can help!

Nigel