Hi Tim - it must be your lucky day. i found one of those "bad boys" and measured it
this is what you see when you are looking from the back and the ground lid is pointing up
there are four switches S1, S2, S3 and S4
when the plug is connected the switches S2 and S4 are closed.
when there is nothing plugged switches S1 and S3 are closed.
G stands for Ground
T for Tip
R for Ring
when you see a cheap multimeter grab it.
i cant even sleep without my multimeter