IS not the gas valve visible when you open the exterior compartment?
All I'm recommending is this
Check for power to the solenoid (NOTE you can use long leads on that test light and hook 'em up when you have it out, He said he cleaned and re-tapped all valves, jets and such so he's had it out) The testing for magnetic field is optional if the coil and the solenoid are only solid as a combined unit then if it has power and is not letting gas pass. it needs replacement
But if it's not getting power.. Problem is elsewhere.
NOTE: if you use a test LED setup. You need not remove it, you can leave it in there forever.