On Wednesday, November 10, 1999 at 12:00:00 AM UTC-8, mattg wrote:

use a heat gun, (essentially a hi-temp hair dryer)
or --very-- carefully with a propane torch. either one
will get the glass hot enough to crack it, so be careful.
also, try not to breathe the vapors.

be patient, and let the heat source do the work.

Be aware, too, there are probably glaziers' points (little metal fasteners) under
the putty, that may have to be pried out of the wood.