Quoted from eraserhead:Is there anything I should be particularly worried about in restoring the ground to this machine?
I'm assuming this was on route at some point in time and the location didn't have a grounded outlet - and the operator elected to use a pair of side cutters instead of a cheater plug.
A 3-prong wall outlet probably wasn't available, so the operator just took the easy way out.
It's always best to fix that by replacing the cord.
https://pinside.com/pinball/forum/topic/replacing-line-cords-plugs-wall-sockets-vids-guide