We have a big house with a lot of gigantic leaded-glass windows. The glass is loose in the zinc cames (they're called leaded glass, but they're not lead), some of the zinc is damaged and the sashes rattle in the wind. So we called the local old-window guru who came to remove the four sashes from two windows in a room that I was redecorating. He sent them for re-zincing with the same glass, and reinstalled them in newly-weatherstripped openings with new sash cord. What a difference. Beautiful! Tight and smooth-opening. I can't wait for winter so I can laugh at the cold! (Storms are OK; sooner or later they get replaced too, but right now it's sashes.)
It cost about $500 each window. I wonder how much it would have cost to have new windows put into the same openings (48" x 60")? A lot more than that, I bet, and these windows will do for another 90 years.