This video shows you how to resolve an error code of 81 on your Bally s5500 slot machine. The SRAM clear procedure has to be done in order to remove the code.

Replacement Battery:
3.6V Lithium Battery 1/2 AA

Type into Ebay/Amazon/Digikey etc... "3.6 1/2 AA Battery" and multiple batteries should come up. If your battery was like the one I described with soldered axial leads, add "axial leads" to the end of your search to be sure you are purchasing a battery with those leads. Also do not attempt to unsolder a battery with no soldering practice, the traces on these Bally board are extremely thin and trace damage can occur if you are not careful.