Ok, this kinda pissed me off. I kept getting jams and finally removed the buffer and circuit board. The buffer magnet was installed UPSIDE DOWN from the factory. No wonder. Glad to get it solved, but this wasted quite a lot of my time and caused me hours of frustration and failed prints.
The magnet likely wasn’t flipped from factory, if it was the printer would never have worked from day one.
It’s more likely that it flipped in the slot at some point. A few users have reported the exact same phenomenon, on printers that were previously working properly.