Batteries were a staple in pinball machines because they kept high scores and various settings. The problem is that many owners did not realize certain facets of their machines run on batteries until the machines stopped working.
The games stopped working because the batteries leaked acid on the components. It is very important when valuing a game to look at the condition of the batteries and CPU boards to determine whether or not there is damage. In some cases, it can be cleaned up quickly. In other cases, the CPU boards are trashed and must be replaced; which, can run $200-$500 depending on the game.