Stampings on the balance

It's a little difficult to tell from the angle of your bottom balance shoe, but it appears your bottom shoe has "wings". If it in fact does, please take a look at both our S380-27 and S385-27 channel balance. Depending on the depth of your bottom shoe will determine which one of these balances would work for you. You would go with the 2640 option for whichever you choose. 

I'm leaning toward S385-27, if you have the shoe shown below. Just measure to be sure.

Alternate view of 15-004