Taken from the old Pinrepair guides, yes you should have a Varistor fitted.....
"The Varistor.
Known as VR1, the varistor's job is to aborb large voltage spikes. The first thing the
power cord attaches to is the varistor. If the power line gets struck by lightning, the
voltage spike coming down the power line can toast anything in its path. The
varistor will absorb this spike and short itself, preventing damage to the game
(electricity will take the shortest path of least resistance). A blown varistor is
usually obvious; it will no longer look like a red disc capacitor, but will be a molten
mess with two wires attached to it."
