Peter et al,

I didn't do this with the cylinder in the car, but rather on the bench.  I
needed to move the reservoir to a new master cylinder.  I was not able to
pry it out.  I applied as much force as I dared without risking breaking
the thing.  So, since the new master cylinder had new rubber grommets in
it, I carefully destroyed the grommets in the old one to get the reservoir
off.  It was quite hard to get the reservoir into the new master cylinder
as well.

Mike
'84 GL