If neither of the seats work, it seems pretty likely that they are not getting power. A fuse can be bad without looking bad, and the contacts of the fuse can also be bad. The fuse can be tested with an ohmeter (infinite resistence= working fuse) The leads can be tested using the volt setting of the same device, with the switch on.

I had a Toyota that would have the AC stop working every five years when the fuse corroded a bit. You could not tell from looking at it. Polishing off the ends with steel wool fixed the problem.

I suppose you could pry out the switch and see it the swith is getting voltage. It is unlikely both switches would stop working at the same time.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)