HELP IDENTIFYING CHANNEL BALANCE

This information gives me an idea, but it doesn't pin down the exact balance. It looks like that metal channel is 27" by itself. Confirm that.

If so, you have S380-27 or S385-27, depending on the bottom shoe attachment. They are identical except for that attachment. Measure as shown below. You need Series 380 for a 1" shoe and Series 385 for a 1-3/32 (or 1-16 ish) shoe.

Then, you need to look for a printed code on the balance, or weigh your window sash, whichever is easiest. This is the most vital part. You can't order without one of those two.

Comparison of 15-004 and 15-005

S385-27, it is. For your sash weight, you want to choose a 2640 weight option.