Replacement window balence

Thanks for posting. I am confident we can replace this balance, but I'd like to verify one further detail. Can you show us photos of the 'guts' or underside of the metal channel? There is one outstanding feature I want to verify. We'll be able to move this along from there. 

Perfect, thanks. This is most likely either an S380-17 or S385-17 Channel Balance. The only difference between these two balances is the 'depth' of the bottom nylon shoe, or the measurement from heel-to-toe. See the diagram below for reference. Measure your old balance's shoe depth and see if either choice matches what you need. In either case, for a new stamp option, choose 1650.

Comparison of the S378, S380 and S385 balance shoes.