JZGRDN 36642 B294 Foot Switch Compatible with Ridgid 300 535 Pipe Threader Threading Machine

I purchased this foot switch for my Ridgid 535 pipe threader, wiring was straightforward (or so I thought) as soon as I plugged the machine in, it tripped my GFCI outlet, I was ready to send it back, changed the wires around and same thing happened, I opened the foot switch and found they had the ground wire (green with Yellow stripe) connected to a terminal on the switch terminal, instead of the ground screw of the housing. Changed that and it works perfectly.