3/8" channel balance top sash guides

Question

I bought some Series 800 balances, order 1348800, but they don't hold my window open.
Is it because the top sash guides are broken? I've seen two questions where customers shwed pictures of these top sash guides, but you never recommended the correct replacements. It was 77-60649 and 77-40323.
What is the right top sassh guide for my window? And why doesn't my window stay open?

Paul · Accepted Answer

Thank you for posting on our discussion board. We believe you can use our 18-036 top sash guide in place of your current one. This part is used with the Series 800 balance. Your screw hole measurement should match up to ours. Measure it to confirm this information is accurate. As for your balances not holding the sash up, I noticed you recently purchased the S800-30 with a 29B option, which supports a sash weight of 8-14 pounds. Did your original balance have the same stamp option as the replacement? Do you happen to know the exact weight of your sash? Please get back to us and let us know.