key worked one minute then wont, but the engine starts with hot wire

Could it be a relay or solenoid gone bad?

Do you have ANY power at all?

Check all the connections at the bulk head and check the fuseable link

Possibly a bad ignition switch???

Sounds like what I'm going thru now, I need a ignition switch. Check for power at the yellow wire at the starter relay with the key in the crank position.

With the key turned to the start position, check for 12 volt at the start relay on the BLK-YEL-TR Wire. If you DO NOT have 12 volt your ign.switch is bad.
If HAVE 12 volt yor start relay is bad. You can use a jumper wire from the Red wire to the BROWN wire at the start relay which bypass' the start relay and if it cranks your solinoid is O.K. See the schematic.
http://www.mymopar.com/downloads/1966/66DartB.jpg

There was another post here where some one didnt believe me when I said the neutral switch was the ground for the relay, wished I remembered I would like to show him your schematic.

Yea King, I did'nt mention the neutral safety could be his problem. Maybe he'll post what he found wrong.