If a tool requires a grounded plug, there is a purpose. Cutting off grounding plugs for any reason exposes the user to electric shock, and make the person a hack. If an old EM has no built in game grounding, you add basic grounding for safety reasons of the player and general maintenance protection of the technician, not to tap added power. If a person is asking to fully modify an older game for convenience of using modern polarized electric tools with or without a grounding pin, this is not advised. The reason is straightforward, the game never supported this function, so do not do it, use an external connection for necessary tool power. A standard work light bar usually has several with grounding. I actually have seen people do some less than intuitive things off both the power and neutral leads of older games. Don't advocate poor advice out of convenience.