Successfully swapped mine out for the first time, as usual Pinside delivers with exactly the info I needed. Considering mine is over 9 years old, I assumed it was about time (although it might have been already swapped by previous owner). My virtual pinball rig that is 11 years just had the same battery finally die (never replaced!), so sometimes the batteries can chug along for an extended period of time. Only part that felt weird was swapping out the batter with the machine on ... one slip and you could be missing a chunk of finger and shorting out everything due to blood! Or more likely in my case I would somehow drop the new or old battery and short things out that way 
Nope, I'm not a surgeon if anyone was wondering.
(Topic ID: 178926)
San Jose, CA
