I have the problem with some old double hung sash windows. I tried the heat gun method with some success but still managed to crack a few panes not from excessive heat but from pressure applied scraping the putty out. I found that the glass was not necessarily evenly supported by the rebate ok the other side.

I've switched to using a multi tool with oscillating saw blades. With a little care this is a little easier and quicker, but patience is the key word whatever the method.

On 02/19/2017 9:34 PM, wrote:
I have the problem with some old double hung sash windows. I tried
the heat gun method with some success but still managed to crack a few panes
not from excessive heat but from pressure applied scraping the putty
out. I found that the glass was not necessarily evenly supported by the
rebate ok the other side.

I've switched to using a multi tool with oscillating saw blades. With
a little care this is a little easier and quicker, but patience is
the key word whatever the method.

Unless actually replacing panes, probably totally unnecessary to remove
any that isn't loose...don't _make_ work for work's sake...

--