>>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 on 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.
>
>> 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.
Also, old window caulk can contain asbestos
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John T.