I have found a person who knows what that little black device is...and he actually has some (however he has just moved and they are packed away in a box somewhere).  He has successfully repaired these Fault Modules using them.

The device is an SCR - Silicone Controlled Rectifier.

This is the definition of an SCR:

An SCR, or Silicon Controlled Rectifier, is a solid-state electronic switch with three terminals: an anode, a cathode, and a gate. It acts like a diode that can be turned on and off, conducting current in only one direction when a trigger signal is applied to the gate.

So it appears that I have found a source......someday when he is unpacked!