Tom from SWISCO responded:
August 9, 2016
Thanks for posting. The only difference between the 15-001 and 15-002 is the depth. If your depth is 1-1/16", I think you're fine with the 15-001. It's likely it was once 1-3/32" but wore down over time.
If your sash weight is 17.5 pounds, then I would recommend the 2630 option instead. 2640 is a little too strong. Did you ever find your old balances were a little tough to operate? |