No Start After Alignment

[1983/300CD]

I got everything adjusted, removed the spreader bar, closed the hood, then jumped in a turned the key. The glow plug light burnt dimly and the tachometer needle started a weak dance between 1 and 2K. After a second or two, the glow light went bright yellow, the tach needle red-lined, and a short buzzing sound came from somewhere. But the car didn't turn over.
I've heard stories of a neutral safety switch. I think the PO might have said something about it being disabled, but I wouldn't swear to that. Does this problem sound familiar to anybody? I did put it in neutral in order to roll it over the slip plates, if that provides any more useful information.