replacement of "1840" channel banlance

Hello, thank you for posting,

It appears you have either our Series 351, with a 15-002 bottom attachment, or Series 390, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. 

The length of the metal channel excluding the nylon attachments should measure 19" long and you will need a 1840 stamp option. Please review and let us know if you have any additional questions. 

Comparison of the S351 and S390 balance shoes.