Need help finding correct replacement Sash Balances

Good evening,

Both the sash balances in the window I am trying to repair are defunct.

Please see the pictures above for reference.

The length of the balance (not including the shoe) is 28 inches.

There is a patent # stamped on the side but no other markings.

The patent # is: 5737877

The width of the shoe is 1 and 1/4 inches.

The weight of the sash is 22 pounds

The pivot bar(s) are 2 inches long by 1 and 5/16 inches wide and are 1/8 inch thick.

Any help you can provide in directing me to the correct Sash balances to purchase would be greatly appreciated.

Respectfully,

Philip