I have 6 windows that needs 12 channel replacements

Thanks for contacting us. We can supply these balances as a custom order, due to the heavy duty springs. We can use the 1365 for both the 17.5 pound sash and 20.2 pound sash, since it has a weight rating of 18 through 20 pounds.

The 21.6 pound sash is a different story. Your original stamp indicates a much heavier sash weight at 36 pounds. Can you confirm the weight on this one?

If you are confident that it is 21.6 pounds, then we have two possible options for you to pick from, but unlike the other two this is calibrated to one very specific weight. You have two choices: 21 pounds or 22 pounds. I'd like you to tell me which one you want to go with.

Finally, to go back to your original question, I am certain that these are the Series 390. The shoe depth probably just wore down over time.

Hey, Jason. If those windows were always hard to close then the heavy duty spring was absolutely the problem. I don't know what the installers were thinking using something that strong for such a relatively light window, but these things happen sometimes. That won't be an issue with the new hardware.

I will email you an order link and price quote right now for four balances of each size requested. Please let me know if you  had any questions or if you needed anything else.

For reference, the 1365 stamp is for 18 through 20 pounds and the 13DS22 stamp is for 22 pounds.