Need help identifying balances

Question

My son purchased a townhome that's in need of new window balances. The bottom balance plastic ends have been virtually destroyed. I managed to salvage part of what appears to be the bottom of the balance.

A number stamped on the back of the balance is 33400 with "B.S.I." stamped next to the number. The balances are 34" in length.

Thank you so much for your help

Doug

Bob · Accepted Answer

Hey Doug. Is there any other window in the house that has balances with the bottom nylon fittings still intact? Otherwise it will be difficult to say for sure precisely what bottom nylon shoe was on those balances, which we need to visually ID to confirm. That said, based on the fragment you're showing I have a feeling this is probably either our Series 380 or Series 385. The side tabs is what gives it away. The only difference between these two balances is the depth of the bottom nylon shoe, as depicted in the picture below:

Comparison of the S378, S380 and S385 balance shoes.

The Series 380 has a shoe that's 1" deep; the Series 385, 1-3/32" deep. Now, as you probably surmised, if you can't produce a balance with an undamaged shoe, it's going to be really tricky to determine this. That shoe depth does indeed affect window compatibility. In a worst case scenario, what you could do is opt for the S385-34, with a stamp option of 3340. If it proves that the shoe is too deep for the window, you could sand it down slightly with sand paper (basically turning the Series 385 into a Series 380). Just note that if you opt to do this, modified balances are not returnable.