Replacement Channel Balances
I am confident we can help, but Alcan windows use a few different types of channel balances. Seeing pictures, specifically of the nylon fittings on the top and bottom of the metal channel, would be best. I'll do my best to ID this balance from there.
That's a huge help, thanks! Based on what I see here, you have either our S380-27 or S385-27, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.
Sure, that's the top sash guide. Yours is a match for our 18-161.
Yes, that stamp implies that your balance is in fact 30" long, not 27". That is the only change, though. You will still need to measure your shoe to determine the right Series.