In message , Grunff
writes
tim wrote:

This is simply a matter of removing the beading,

This is the hard bit though - especially if externally beeded (I
have no solution, I gave up and left mine misty and sold the
house on like it)

It really depends on the type of bead - some come off very easily,
while others will have you swearing for days.

And you're right of course - external ones are much worse.

The trick I've found is to pull out the rubber seal on the _inside_. A
blunt 1" chisel helps pry the first bit out.
Having removed the inside seal, the load on the beading is reduced and
it easily pops out.
IME anyway.
Reassembly is the reverse as Haynes always say.
(Although I remember doing this on a 18" x 30" kitchen opener. Put the
new unit in, poped in the external beading, went inside the slide the
seal into place, only to have the beading fall out the frame, followed
by the unit. Managed to grab hold of the unit as it fell way from me and
somehow man handled it back through the window frame. So maybe thats not
the best method.....)
--
Steve