Peter Saffrey wrote:

snip

My problem is with actually removing the panel. I assumed that what I
needed to do was remove the black rubbery seal from the indoor side of
the panel and then unclip the plastic mounting and lift out the panel.
However, the black seal is pretty certain it wants to stay where it
is... I've managed to lever out a few inches with a pair of pliers and
a lot of effort, but this is making me wonder whether I'm doing
something wrong. The bit of the seal that goes under the panel is flat
with ridges on it, but even in the section I've managed to pull out,
it seems to continue around the edge of the panel. My questions are
these:

(i) Am I trying to remove a seal that should not be removed? If so,
how am I supposed to get the panel out? Is there some other technique
I should be using?

(ii) When I replace the panel, do I also replace the seal? If I still
have to remove the seal I think I may leave it in a bit of a state...

The seal comes out complete with the 4 pieces of beading holding the bottom
panel in place. With a nice big chisel you should be able to pry the beading
out (carefully) without marking it.

You'll have to remove either left+right or top+bottom beading first as one
pair holds the other pair in.