Spring cover for a BB740 window

Thanks for writing in! It appears you are looking to replace the tube cover on your window spiral balance. We do not carry the replacements for them and I am not confident that this is something you can obtain a replacement for. 

That said, you'll need to replace the entire balance. I am happy to recommend a replacement for the balances you need but you'll need to confirm a few details before we can move forward. Take a look at the video tutorial below for reference.