Given the fault seemed to affect all functions, my money would be a voltage drop in something common to all functions.

I certainly wouldn't be unwiring such a complex switch just to test how it works, when you can get far more accurate readings by testing it under load, by measuring voltages...

Plus, the fault could quite easily be with some of the other safety switches in the control circuit.
The only thing I'd do now everything is working, is double check all the connections at the switches, and work them a few times to work the contacts. If the switches haven't been operated for a while, the contacts could oxidise causing a voltage drop, and working them a couple times can be enough to get them working again for a while.