Searching for unique channel balance

I have old Alcan windows. Single tilt with broken channel balances. on back of channel it says: UNIQUE 10/31/96 15-0(?)-30

The channel is 16"metal end to metal end and true 1/2 " deep x 1/2" wide. there was no nylon guide riveted to top and the bottom has plastic piece riveted flush to bottom. it is 1/2"wide and 5/6" high with a hole in the bottom that the string passed through.

can you help?

I dont know how to attach photos to this. I know how to email pictures if there is an email address you can look at though

Thankyou, Marsha

Here are the photos

Thankyou a thousand times over. the 770 balance you suggested was perfect. You are BRILLIANT!!! Now I am ordering more to fix the other broken windows of the same size and will attempt the larger windows after that.

you amazingly got me the channel balances I needed for my small windows. They work great now. Next I have 2 larger alcan windows. Single hung. the old channel balances are 28" long. True 1/2" deep channel by true 1/2" wide. Again,looking just like the other small windows they have no nylon guide on the top and a hard plastic piece riveted on the bottom that the string passes through. the numbers stamped on the back of the channel : UNIQUE 27-D-40
Can you help me out with these puppies?