Square channel tracks, length in pics and even sent plastic cover for help

Thanks for reaching out to us! Take a look at the S770-33 with the 33B stamp option. This mounts to the top of the window track with a screw, but please let us know if yours installs differently. Review the specifications and let us know if you have any questions. 

It does, yes. Are you only measuring the metal channel? If it's indeed 34", we'd need you to get back to us with the exact weight of the sash so we can determine the appropriate stamp option for your replacements. 

The 33B stamp is calibrated for a 14 to 20-pound window sash, but there are different weight ranges used for the 34" length, which is why we need the precise weight of the sash. Choosing the incorrect stamp option may cause issues with the window's operation, such as preventing it from closing.

If the metal channel measures 34" long and the sash is 20 pounds, please see the S770-34 with the 34B stamp option. A pair of balances with this stamp is calibrated for a sash weighing 16 to 22 pounds. 

Just keep in mind that the Series 770 is designed to be screwed into the top of the window track. If yours installs with a clip of some kind, please let us know. 

It sounds like your balance uses an S-clip like the 19-029 or 19-030. We don't recommend drilling a new hole for the balances as there's a risk of damaging the jamb. We can supply the Series 770 with a rivet in the top hole, allowing it to be used with the 19-029, but this would require a custom order. 

Let me know if that sounds good to you and I can draft a price quote.