Check each plug on the machines if it is the kind you can take off and make sure its a 3 prong and the white is in the silver screw.
Household electricity has neutral and hot. Well in theory both are hot because its AC but in the house one lead is designated neutral since in the panel it connects to ground.
You will not get shocked on the white only the black. That is why on 2 prong (in the last 20+ years) there is one plug that is wider. This is so, like on a lamp when you touch the screw part when screwing in a bulb on a live lamp you wont get shocked.
Check the plugs first. Then check the outlets.
Home Depot sells a plug tested for a few bucks that will tell you if the outlet is wired wrong.
Do these 2 things first then you can move on the machines inside (Maybe the 120 is wired backwards in the machine)