Channel Balances

It's tough to make out what you have from these photos, but I'm reminded of our Series 765. I recommend that you start by looking at this product and seeing how well it compares to your original assembly.

This still looks similar to our Series 765. Have you looked over this product yet? If so, is there any reason why you don't believe it will work?

If I were you, I would use an undamaged balance as a point of reference. Your current balance seems to be missing many of its components so it may not be the best thing to used to confirm.

It's not possible to gauge weight based on window size alone. There are too many other variables to give a precise estimate. 

Your old stamp of "29 3" should correspond to the 29-3 option for our S765-30, but if you had any doubts then you will need to weigh your sash on a scale.