It appears you have either either a series 351 or series 390 channel balance.
The difference between the series 351 and series 390 balances lies in the shoe.
Comparison of the S351 and S390 balance shoes.
The series 351 channel balance has the 15-002 shoe while the series 390 channel balance has the 15-001 shoe. The 15-001 shoe is 1/8" larger from front to back.
You will need to measure your bottom shoe to find out which balance series you need.
Please let us know if you have other questions.
