Grounding yourself when working on solid state machines is a good idea
because of the possibility of static charge damaging solid state
components. But be careful--grounding yourself improperly can be
fatal! If you are grounded and hit a high voltage it could kill you!
The best way to ground yourself is by a grounding wrist strap. The wrist
straps have sufficient resistance, such as a 1 Meg ohm resistor, that you
will not electrocute yourself accidentally while working on a pinball