Series 385 balance question

Quick Learner from Westport, O.
Hello,I have 30 year old Alpine double pane windows.Am in the process of changing out the balance rods.Have done lots of research so know all windows take a 21 series 385.bottom foot is 1-3/32.But, some say 204 Caldwell, some 2090N BSI, 204KT CMC 2. 2040BSI.The only difference in the balance rods are the bottom of the height (5/8). Some have a rib on the bottom, some are just straight.My problem is I can not get the window back in the slot with new balance rods in place.Can not get the window far enough to the right to get the other side in the slot.there is a difference in the bottom plastic guide as far as length goes..heights are the same.HELP thank-you
2 Replies
Bob
Bob from SWISCO
SWISCO
Expert

Thanks for writing in. It's possible these differences are just pure aesthetics and won't matter in function, with the exception being the stamp options needed for each set of balances. But I want to be certain, because I'm not certain what you mean about the 5/8" difference in height. There's a chance you could be working with something custom here. Can you show us pictures of each of the different balances, side-by-side, with close ups of the nylon fittings at both ends? That way I'll know exactly what you're working with. Many thanks.

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