Andersen window balance replacement

first things first. Your YouTube video was extremely helpful. I have to replace both balances and the numbers visible on the hardware are 11600-17 on the flat bottom under the Andersen logo. On the short side where the balancer was stapled to the wood shows 1291. Please let me know what part number I need to order so I can fix the window.
Thank you very much,
Dave Tierney

My son, good set of eyes, was also able to read the entire number on the short side. 5191BL451291.

I also found a number on the window - 2032. The window measures 16x20.5.

Thanks,
Dave