"4290 PE 35"
Hello!
I'm afraid your balance is too damaged to identify. We must see an undamaged version removed from the window. Close-up photos of the top and bottom fittings are ideal.
Yes, the number 35 at the end of the stamp likely indicates the sash weight. However, weighing the sash to be certain couldn't hurt. Note that this would have to be a custom order due to the length, and custom orders can't be returned for a refund.
Thanks for getting back to us. I'll go ahead and email you a purchase link for (2) 42-1/2" long Series 385 balances with the 42505 stamp. A pair of balances with this stamp will support a sash weighing 30 to 36 pounds. There is a 5-6 week lead time as well.
Please keep in mind that we can't be certain the Series 385 is what you have without photos of the end fittings. If the bottom shoe has a pulley wheel built into it, the Series 385 will not work for you. If it indeed has a pulley wheel in the bottom shoe, we must see photos of the end fittings along with the metal clip attached at the end of the pulley cord.