Hi there Ryan.
Thanks for reaching out to us. I'm afraid we can't confirm if the 90-263 is what you have. You would have to remove it and compare the specifications with ours to see how they align. We also have the 90-237, 90-169, and 90-301 face mount keepers which appear similar from what I can see of the old keeper.
As for your other question, it sounds like your balances need to be replaced. Did you always have trouble with the windows or is this a recent problem? In either case, we will need to see an undamaged balance assembly removed from the window to compare to our inventory. We may need more information and photos after that depending on what you have. Just something to keep in mind.