In my experience, Morgan rear brake cylinders are notoriously prone to problems.
Personally, I would get them replaced.
Fully agree. Both rear wheel cylinders were ceased on my 2011 4/4 at 32Ks.
An easy task as you won't have to remove the shoes if you're careful.
The only trick is fitting the retaining clip holding the cylinder to the back plate.
Brake fluid changed regularly but I suspect regular use and packing the rubber caps with appropriate grease (not done as new) are key.
