Im not comfortable giving advice with 240v mains.. but all you are doing is replacing the switch.. what goes to the delay relay is extra and shouldnt be there.. so piss it off. Make sure its UNPLUGGED  to work on and always isolate yourself from the machine when testing on turn on... nice long extension cord so you are far away etc
Anyone with a GTB sys1 should be able to tell you where the flipper wires go... they are all the same.

Good luck mate...