I paid to have my casements replaced. I watched closely. Appeared a
straightforward job Some mounting screws were removed, and the frames
bent left and right not up and down to avoid sill damage. some glass
panes cracked bt not many. a couple windwows were tough and they used
the sawzall. of course they removed the inner trim and tossed it and
covered the outer wood with baked aluminum. buy caulking by the case.

Its been over 10 years since I replaced them, just wish I had done it
sooner.

I would get the argon or other filled windows they really make a
difference and dont conduct cold