I think replacing the rope with sash balance isn't feasible or is it? These ropes are a major short coming of these sash balances if humidity is high humidity environment. Roughly 50 percent of my 30 year old ropes have snapped.
Tom from SWISCO responded:
October 27, 2017
No, unfortunately, it isn't feasible or recommended to replace the sash balance cord. It's far easier to just replace the whole balance, in the long run. Do you need help picking a balance?