Alcan window balances

Hello, Dan. To my knowledge, Alcan windows use generic balances like most other window manufacturers. I don't think you need to do anything special to remove them. Where exactly are you running into issues?

Concerning your second question, you can ignore that last letter for each stamp given. It's not important, it's just a branding mark left by the manufacturer. The only thing you need to focus on are the main four numbers; in your case, 2920 for the first and third balance and 2020 for the second balance. 2920 and 2020 are obviously not the same stamps, but that has nothing to do with the "w" or "y," which are irrelevant. 

It's also important to note that the stamps alone don't tell us what you have. Those aren't product codes in any way, they only indicate the calibration of the spring and, to a lesser extent, the length of the metal channel. The only way to ID a channel balance is by the physical design of its top and bottom nylon fittings.

As mentioned before, you probably have generic parts, so you won't be able to ID what you have based on the name brand alone. Physical details are the only way you're going to find a match. There's no way around that. We need you to remove the parts in question from the window and show us photos of them without obstruction and in undamaged condition. 

For the balance, I need to see the top and and bottom end, as well as the metal clip or hook at the end of the cord. For the top sash guide, I need to see it from the front and side; think of it like a mugshot.

That top sash guide is a match for our 18-161. I am confident that this product is what you want.