poor performing balances

A quick learner from Pennsylvania says:
I just got 18 S385-13 channel balances. The balances appear to be a good match with the old parts, but upon installation of the first pair, my window is hard to lift, it sags when I let it go in the up position, and it makes a springy, boingy sound when it's moving.
What is wrong?

Profile picture of Tom
Tom from SWISCO responded:
Sounds like a problem with spring strength. It's possible the balances you ordered are too weak.

I note you chose the 1210 option. Are you sure that's what you needed? Two S385-13 balances with a 1210 option can carry a sash weight of 3 through 6 pounds. How heavy is your sash?
A home owner from Pittsburg CA says:
It is 3 pounds. These are very small windows. 1210 was stamped on the old hardware.
Profile picture of Paul
Paul from SWISCO responded:
I see. In that case, I see you ordered 18 of these balances. I would try another pair in another window and see if you have the same problem. I'm trying to see if this is just an isolated problem with those balances and that window. If you can confirm one way or the other, we will work from there!
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)