I just bought a 84 Chevy C30 with the 6.2L diesel. This is my first diesel. I'm working on a few issues with the truck. First thing is with cranking. Most of the time, the truck fires right up but every once in a while, all I get is a single click. If I keep trying, it will eventually turn over. The batteries are new and check out good. The alternator tests good. Where should I look next - starter, relay, solenoid? Also, the glow plug controller has been bypassed with a manual glow plug switch.