old block and tackle style rod and spring balance (pat 5737877)

Question

I have these old block and tackle balances in my windows (circa 2001) and some of them have failed. Mostly, the shoe has failed - it's jammed and in some cases damaged. It's an unusual shape of shoe, not a t-shape but rather a single sided sort of cam shape, as shown in the photos. This one is undamaged.

Ideally I'd like to replace just the shoes and pivots where those have failed and the rod style spring balance is still working, but some are entirely missing - some windows have just one balance, some have two, despite being otherwise identical. I suspect a past owner resdistributed them rather than repairing the broken ones.

What would be the appropriate replacements?

Oh and for future searchers, the only markings on these are "pat 5737877". I found some other posts here with that, but with different shoes.

Emily · Accepted Answer

Hi there!

Thank you for reaching out to us. I'm afraid you can't replace just the shoes so you will need an all new balance. With that said, we recommend the Series 775. You'll just need to measure your balance's bottom shoe and weigh your window sash to choose the appropriate spring strength option. There's a chart on the S775's product page that will show you which option you'll need based on the weight of your sash.

If you have any further questions just let us know!