Channel Balance Question

Hello there. I'm confident we can help, but I'd like to confirm a few details first. 

• Can you confirm that the length of the metal channel on these balances, not including any attachments, is 50"? If so, a stamp starting with '46' would be unusual. Please confirm. 
• I'd also like to see a photo of the entire stamp on the metal channel. 
• Additionally, could you tell us the weight of the window sash that a set of these balances support? I am assuming all 20 balances are for identical windows. 
• Finally, I'd like pictures of the top and bottom of the balance, so we know what attachments are at both ends. Assuming this is indeed a Series 770, there can be considerable variation here, so it's important to see what hook, clip, or shoe is at the bottom, as well as how the balance attaches to the top of the window jamb. 

We'll do our best to get this all sorted for you from there. Many thanks. 

That's a huge help, thank you. This looks like a pretty heavy duty balance. I'd be happy to check on the availability of this size for you, so please give me a little time to look into it and I'll get back to you ASAP!

I did have one last question for you in the meantime: the "L" in your stamp indicates to me that this balance is being used for the lower sash. Can you verify? That may be a factor that comes into play for weights as high as this.

Thanks again for your patience. We're currently talking about this assembly with the manufacturer. I believe we're getting closer to resolution, but before we get any further I'd like to see a photo of the rivet at the top of the balance. We need to know if it's the 1st or 2nd hole down from the top; seeing a photo of its position would be the most helpful, if you can get that for me.

That works for me! Thanks so much for checking. Please give us a little more time to verify its availability and we can then get the ball rolling on this.