Score all the angles with a sharp box cutter. Cut the paint and caulk areas.
I have used a hair dryer on some windows if the season is Winter to dry the wood, thus shrinking it somewhat so that this process is easier.
It would be better to tackle this job in the hot summer time anyway.
once the intersections are scored, then its just pushing and controlled banging. Do not do as many people do, use a hammer or use your palm as to break the glass and cause major artery damage.
The pushes should be wide spread and over great areas not like a hammer blow to a one inch spot.
No easy solutlion, just work at it.
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