Free B&D Dustbuster - needs new battery

I’ve got a 7 year old B&D cordless Dustbuster that needs a new battery. It currently has a worn out NiCd 14.4V. Exact replacements are hard to find, but it also seems possible to upgrade to a LI battery if you know what you’re doing. I don’t, and I don’t use it enough to spend the time figuring this one out.

I know this may barely be worth it to fix, but I though it was worth offering before I trash it. Thanks!