[914Ghost]

Andy-
when you turn the key to 'start' do the "idiot" lights in the combo guage dim a little?
If so your starter is drawing voltage from the battery.
It generally means low charge or starter and/or wiring problem.
At least you can (nearly) eliminate ign' switch/wiring.
Your tranny ground strap will most likely not be a problem since you said you checked it out recently- and if needed the engine will ground through the damn throttle cable burning it in half.
If your battery is charged and you get NO dimming at idiot lights, use a jumper switch at the starter (battery cable to small spade connector) (or screwdriver of you like to weld).
If it dont crank get another starter.
HAppy Holidays!!