Peter Saffrey wrote:
Thanks for your replies. My bead is one long piece. I'm not sure what
you mean about using a big chisel - it's wedged under the seal and I
don't think I could use a chisel without cutting off the thin ridged
strip that's trapped under there..

I can also see that once I get it out, it's going to be a huge pain
getting it back in again.


I recently had to remove a pane of glass from a window and suspect the
fitting is similar. From the middle of one side of the rectangle which
is the panel, use the big chisel or similar to knock the beading in
toward the middle of the panel. You should then be able to pull/bend
the beading out of it's channel, complete with the rubber seal.
Refitting is easy enough if you can bend the beading enough to get the
two corners of the last piece in before tapping the middle part in
(i.e. the opposite of removal) I suspect the removable beading may
only be on one side.