On 50s and 60s machines I have the electrical has usually been fine, but 1920s and 30s machines with cloth covered wiring have been shockily bad; all the rubber insulation very stiff and crumbling. It's not always easy to check the conditon of cloth covered wiring, so don't trust it if it's old. Some have taken the bother to rewire with new cloth covered wiring, and there's always a chance a machine has new wiring. A 50s zigzagger I have needs a new ligth switch and the electrical sorted out, so alway check regardless of age. Even brand new appliances have short circuted in the worst of cases.