S303 Question

We actually used to carry that retainer, but we sold our last stock a long, long time ago. As far as I know, they aren't made anymore and nobody has any left. But don't worry, not all hope is lost. I've repaired these windows without them. I think you should be okay with the Series 303 as-is.

First, remove the sashes and replace the balances (and sash guides, if needed). Reinstall the sash and hold it up. Raise the spiral and just before you lock the shoe to the bottom of the sash clip, give it three turns.