Making my own batteries is far beyond my capabilities, especially since I'd have to make my own shell as well (the old battery was removed by the previous owner). But the good news is that I finally got my money back from AliExpress, and found a brand new battery on eBay for $12.35 shipped (model number PA2487U)!
I charged it and it works perfectly. No more having to constantly plug it in. After this post, I'm taking it in the backyard with a glass of wine and playing me some Dangerous Dave.![]()