I tried giving the Sensor
Plug a sharp blow to the the side of the case by slamming it into a
table top like Zimmy suggested in a comment last week.
That brute force cure worked
at bringing life back to this product. Now the Sensor Plug will eventually turn
whatever is plugged in off, and then turn it back on when movement is
detected. I'm just not sure yet what the interval length is.
Not sure if that proves it
must have a mechanical relay or maybe the adjustment potentiometer was
damaged and the jolt brought it back to a proper state of providing
variable resistance.
Yes...it clicks.
Turns out it just needed a good smack.