Identify spring balance and Pivot shoe

Can you please help me identify which spring balance and pivot shoe to purchase? I have aluminum tilt single hung windows. They are M I windows from 2001 that used a string and spring system. The outside casing of the spring balance is Marked "33C". It measures 33 inches long from the top of the white metal casing to the bottom excluding the metal clip at the end. The metal U casing covering the spring and string is a half inch deep.
The pivot shoe is 1/2 inch deep. It has number 4.610.108
The bottom sash weighs 22 pounds.