[Shamu406]

If your solenoid has three wires, red/black/white, the black & red are the hold in coil.  The white is the pull in coil.  If you can, look for voltage on the red & black while the plunger is depressed and engine running.  even a test light will work.  If no voltage then follow the "fire extinguisher" safety.  They interrupt the negative to the coil with a pressure switch on the extinguisher which will be open when depleted.  As mentioned, sometimes there is a bad connection to that loop.  Newell used a four pin trailer connector on most.

If you have voltage then it is your solenoid,  I keep them in stock and can UPS red one if you like.

Hope this helps and not too late.

Gordon,
I think I may need a solenoid, my gen runs fine when I push in the plunger. I went through the "Fire ext. test" with Newell over the phone and the said I need one. What can I get one for? Mine is coach 406, 1996 Newell, 20 kw gen. Thanks!
Cell# 727 510 6345 -  call if you can.