Front panel taken off; not a whole lot in there.
On the left, the filter contact and re-ionization wire, middle has the switch wires, right has the motor.

The problem (as I thought). The fan turned very slowly, and so needed lube.

The motor internals. As it turns out, there were no bearings involved, just straight metal-on-metal sleeves, and some electrostatically deposited crap.
I used some bearing oil from my bike kit, but that seemed potentially too thick, so I added some lighter oil also. The result seems decent, so :-D