Double hung balancer

Thanks for posting. This looks like a 15-087 shoe and 15-086 Tandem Housing. This setup uses Series 180 Coil Balances. To choose the spring weight for these balances, it's best to go off stamps on the coil springs themselves, usually near the 'tongue'. If there is none, give me the exact weight of the window sash that these coil springs support, and I can work it out for you.

Series 180 coil balance diagram

Those stamps tell me that you need a 6 pound and a 5 pound spring, respectively. With a 5 and 6 pound spring on each side, that tells me that your sash probably weighs 22 pounds. You should weigh it just to be safe.

As for installing the springs, we unfortunately don't have a video on these, no. The housings just snap together, though. You can use a slotted screwdriver to pry up the little locking tab and that should allow the housing halves to separate without issue.