Mastic windows Channel Balance
Hi there!
Your balance appears to match our S770-35 with the 35B spring strength option. Note, our balance has a ribbed plain metal channel and installs with a screw at the top of the track. This page here will show you the difference between a plain and ribbed metal channel. Let me know if your balance differs from these specifications and we can work from there.
My apologies for the typo! Our Series 770 also has a plain channel so you should be good to go with this as-is. You can also re-use your pivot shoe if it is in good condition.
My pleasure. Best of luck with your repair and please let me know if I can be of further help!