The encapsulated mercury switch sounds a lot like one of the two
switches that were in the lid of Maytag washing machines in the 1950s.
One was used to sense the water fill level (a metal tube in the center
of the agitator pushed up on a Bakelite "button" in the lid that tipped
one switch).

The other switch was connected to a Bakelite "flipper" that hung down
next to the button.  An unbalanced load would tip the tub and agitator,
and it would bump the flipper and tip the other switch to shut the
machine down.

We had two of these machines in our dining room to wash all the resort
towels; I remember them well, and my dad fixing them often.  I used to
have a bunch of these mercury switches -- now I wish I still had them!

David Dewey