I just installed jbpatch 2.4.1, and kindcalc still isn't working. But there is something I should have thought of earlier. When I copied kindcalc to my kindle, a window popped up saying "The selected destination does not support encryption. Do you still want to copy this file without encryption?"
I don't know if that's an issue, but I would appreciate it if someone could upload just kindcalc.azw2 so I could download it directly to my kindle.