The box is a EMI filter. So, you should get 120VAC from the black to green and black to white on the left side of the filter, you should also get 120VAC on the right side of the filter (black to white wires) if you do not, the filter needs to be replaced. The filter removes any line noise before it goes into the machine. Remember your reading may not be exactly 120VAC this can fluctuate slightly.
You also want to check continuity on the switch which is connected right after the filter. Basicly if power is coming out on the right side of the filter the black and white wires then go to the switch. flick the switch on and see if there is power on the other side of switch on the black and white wire. If there is not, then the switch is bad.
This is not a replacement for the game just an FYI.
ebay.com link » Taishing Tsc 10ba1 Emi Filter 250vac 50 60hz 10a
Very basic meter instruction.