I also found me another #calculator project.
A shiny TI-81 with moderate damage battery corosion. Actually, it just lost a battery contact. I don't know why but I already had a matching battery spring in the dish with the calculator.
Let's see how long it takes me to solder it in.

('Found' as in acquired, forgotten about, lost in a pile of stuff, and rediscovered while trying to manage all the piles of stuff on my desk.)