Pressure washed Super 90 won't turn over

I pressure washed my 1963 Super 90 (perkins diesel) last weekend prior to repairing its leaking injector pump.

The repair went smoothly and she started right up afterward, but after sitting a couple of days she just won't start.

When I say "won't start," I mean she doesn't turn over. No clicking noise like what you might hear when the battery is weak. Simply, nothing happens when I turn the key.

I've checked the battery and it's good. And I can find no obvious shorts in the wiring.

Though I covered the inspection hole behind the starter, and was careful to direct the brunt of the pressurized spray away from places I thought might be sensitive to it, I fear I've gotten something wet that I should not have gotten wet.

Any ideas where to start looking would be greatly appreciated.

Cheers,
Paul

I believe my tractor does have such a safety switch as it does need to be in neutral before it will turn over.

I neglected to mention in my original post that I did make sure it was not in gear!

Cheers,
Paul