You will need some small female terminals that fit snug on the male pins in the connector.  Connect your multi-meter to the appropriate pins in the connector socket.

Like this.

Sorry about the clarity of the pictures.  Best I can do.

With the meter still connected, push the starter button.  The circuit should break, and the meter should read infinity or some very high resistance value.

See how my meter is reading 100 megohms.  That's essentially infinity.

You can clean the contacts, but it is tricky and frustrating.  Do it on a table where you can sit down.  There are small parts inside that are easily dropped and lost forever.  It's a bit like watch making.

There are two screws that hold the switch in place.  This is the first screw.

The switch kinda pulls out of the housing with the wires attached.  That white plastic cover has to be removed but it's fragile and easy to break.  The black plastic piece has barbs.  You must depress the barbs a bit in order to remove the white plastic piece.  You gotta be gentle and go slow and have about six hands and thirty fingers and x-ray vision.  There's springs in there and they tend to pop out and get lost.  Good luck.

A little bit of work with some SkotchBrite pad and the wiper can be cleaned up.  That assumes it isn't severely pitted.  See how there is a pit in the wiper (green arrow).  It's not too bad, but this switch isn't gonna last a whole lot longer.  

Note that in this view you can see a spring that pushes the wiper (yellow arrow).  Alas, there is a spring in direct contact with the copper wiper, so it gets cooked good when the switch starts goin south.  If you get into this switch, check that spring.  Make sure it isn't dead soft.

Same deal with cleaning the contacts.  SkotchBrite pad and some electrical contact cleaner should do the trick, provided the contacts are not severely pitted.

DragBike, you are the man! I finally got her up and running. Here's what went down:

I focused on the switch apparatus, as you suggested, taking it off and meticulously going through the points to clean it. On the actual ON - OFF swith itself, I removed everything and cleaned the copper connectors. Put it all back, plugged in the tank, and voila! Lights. But here's where it gets interesting. I then peiced everything back together, check as I went to make sure I still had power. When I got the tank secure, there was none again. I move that big section of wires that was plugged in to the ON - OFF switch assembly, and it worked?? So, I tightened everything up and now am a go to finally take it back on the road. Hopefully, it stays together. I wil keep you posted.

Thanks again Mike.