There are no shorts. However, there was obvious damage where a pin of U660 had been totally crushed and was not in the socket. Unfortunately, that was not the only problem.
It has no trigger at all now, no internal, external, delayed, or even single sweep (which just gets stuck in ready). However, the trigger does fire once each time you mess around with switches, so it's not totally fried. I have also checked the diodes and transistors on the trigger board (roughly, as in in-circuit).
I'll see if trying to calibrate it does anything or reveals something.