Hi Brad ! Yes, I mean the internal battery for memory backup. She worked for nine years, then the display started working intermittently, then stopped completely incorporated. I had the address of the website where you can order the original battery, it seems in England, but I lost it. Casio MZ 2000 I felt very comfortable even used as midi. Mechanic keys very comfortable. Hi Mike ! I also tried to replace the battery yourself. But I'm not such a good specialist in repairing electronics :-) You are right it is necessary to find a good specialist. But unfortunately I lost the original battery and now I do not remember its characteristics.