window channels

Hello, thank you for posting,

It appears you have either the 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.

To move forward, please provide the length of the metal channel excluding the nylon attachments. We will also need to know the weight of the window sash. The sash will need to be removed and placed on a bathroom scale. 

Comparison of the S351 and S390 balance shoes.

I believe you are referring to a top sash guide. To further review, we will need to see pictures of the original part where we can see an undamaged face view. From there we can compare to our selection to determine if we can provide a suitable match. Thank you!