Simonton window- balance needed

It looks like the old balance cover has been replaced with something like our 15-204, which uses 3/8" wide coil spring. See our Series 165 coil balance and 15-111 pivot shoe and carefully compare our pictures, information, and dimensions to your own hardware to confirm. I highly recommend removing your balance system from the window to make sure the parts I suggested match up. I only have your cover to work on, which only tells us so much.