Ok.
Yes, @ScottNH, plastic washers were in place. I looked closely at every wire inside the box and nothing appears damaged.
Removing the box from the table chassis had zero effect on the freezing issue. I performed 5 cuts; FireControl froze instantly each time. One time it froze with torch speed registering “53687…” but I do not believe the torch was actually traveling quite that fast. 
I also had a “torch moving before cutting voltage sensed” error, while the machine was cutting normally.
So, I re-isolated the work piece and clamp as before and performed two successful cuts, back to back.
So, the voltage is not entering the electronics via the table chassis. That leaves the limit switches, the motors, and the IHS wires, correct? I’ll start with the limit switches since they’re the easiest to disconnect.