The seal slides into a slot on the bottom of the window frame. The windows are 22 years old so the seal has dry rotted on a lot of them or stuck to paint and ripped off.
The same seal is also used on top window frame but they are in better shape than the bottom seals
Bob from SWISCO responded:
September 22, 2020
See our 58-053. Look over the end profile dimensions and see if you think this could work for you.