OK, so I removed the gauge cluster on my '67 to put in a mini tach and while I was at it I removed the ignition assembly (the thing the key goes into) to seat it properly - it had slipped out of the groove that holds it in place. Of course, after I put everything back together I get NOTHING when I turn the key to start the engine. The wires seem to be connected so I'm not sure what I did. I noticed that there is an inch square cube thingy that attaches to the ignition assembly. My Shop Manual says it is a Circuit Breaker. There is a purple wire that runs from it to the heater/AC switch. Actually, I have replaced the interior heater/AC controls with an Old Air Products package so that Purple wire connects to nothing. My question is - what does this "Circuit Breaker" do? Could it be causing the problem? Since the Purple wire does not connect to anything can I just remove the "Circuit Breaker"? Thanks for any advice.  E.