I don't know the year of your car but from 1993 onwards they changed braking systems from girling to Lockheed. I rebuilt mine last year and on the back plate there was a rubber bung on each one in the right spot to release the auto adjuster.
This link draws the picture for you.
http://www.gomog.com//allmorgan/APBRAKES.htmlIf you want part numbers and a good price on OE brake bits pm me, based on my rebuild last year no vested interest.
Dinitrol seems to be favourite but I'm not an expert.
Dave W has a fix for the wing starring on his how to section.
A friend of mine stuck some sort of bitumen flashing stuff under his arches and that did the trick, mine has got so much black underseal on it and doesn't have that problem.