I think it was Einstein who said that once you've eliminated the possible, then the answer must be the impossible.
Let's back off, and start over.
The first question: is it the circuit of the appliance? I say just replace the appliance, and see if the trouble goes away.
FWIW, I had a similar problem some time ago. While a bad power strip was found, and a bad refrigerator compressor as well, the real culprit was a cracked / broken bussbar.
