No start issue: Ignition, NSS or Glow Plug Relay

[mtgoz]

For the past year I've been trying to track down a no start gremlin on my 83 SD. Intermittently you can turn the key to start and there is not even a click at the ignition. All new glow plugs and all lighting works fine. I can jump the two wires at the junction box by the battery to bypass the ignition and it will crank. Now I've replaced the ignition lock and switch, adjusted the neutral safety switch and still have the issue. It happened to me last Friday after driving to the coast I stopped at the store got back in the car and nothing. I popped the hood attached my jumper wire and nothing, it would not crank. I tried again twice more and still nothing. On the fourth try I let the glow plugs cycle and jumped the junction box and it started only after the glow plug relay had clicked. I was tinkering with it a few minutes ago and sure enough the jumper wire would not start the car until the glow plug relay had clicked which is about 30 seconds after the glow plug light goes out. Is this typical for the glow plug relay to prevent the car from starting at the junction box? Could this be the source of the no start issue using the ignition as well? Any help would be appreciated.