I've got the Girling part numbers for the Series 2 set up at home (I'm in work at the moment) but from memory its based loosely on the Austin A40 with the drums being a Morgan specific part.
Couple of thoughts:
Have you checked the brake drum for ovality?
How recent are the flexi hoses? One could be breaking down causing the brake to lock on?
I'd suggest transferring the brake shoes and drum across the axle to see if the fault moves across.
Arwyn
