Cursitor Doom wrote:

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I assumed it was tucked between those resistors to sense any higher than
usual warming in them. It's marked 76 degrees C in the case of this one.
I'm guessing it (since it's in series with the live line) that if the
temp rises above that level it will wind back the current, but this one
has blown completely open-circuit and maybe that's what it was designed
to do. Nothing visible, just on testing for resistance.



** FFS - it's a common thermal fuse.

https://www.amazon.com/10Pcs-Microte.../dp/B072SV9QFB

A spring loaded contact inside is held together with a wax like substance that melts at some desired temp.

Likely the unit was made to overhead by being on top of the blanket and insulated by bed clothes.



.... Phil