In article ,
"john" writes:

Why can't the panes be separated, cleaned and then re-engineered into a
unit?? No glass cutting or supplies needed (other than the edges).

They can if you can take it to a sealed unit fabricator
and live with a large hole in the wall until it's done.
I was warned to dismantle and clean up the glass myself
if I did this, as they may not do that well enough, and
it is annoying to have a nice newly sealed unit which is
still dirty on the inside. Make sure you record how thick
the unit was before dismantling though. I didn't actually
do this as the frames needed replacing and the rotten
sash boxes removing too, so it was new windows all round.

--
Andrew Gabriel