Need Support With Confirming Aftermarket Parts - Pivot Shoe Replacement

Question

I have a replacement (double-hung - tilt in) window (36"x42") that has defective pivot shoes and could that need replaced that are (1.5" x 2.5") in size. The existing springs have no stamp on them as they're too old. The wondow sash weighs between 28 - 31 pounds.
please provide any support if possible with what part numbers I should be purchasing to replace essentially what's in the two attached photos

Thanks Again

Bob · Accepted Answer

Hey there. Looks like you might have the 15-177 Pivot Shoe, which works with the Series 152 Coil Balance springs sold separately. If there are no stamps on the old coil springs, we'll need as precise a sash weight as possible to determine the spring weights needed. Using a bathroom scale would suffice. See below.