I don't believe it was just grit. I could feel part of the light (the three branches where they met the base) vibrating, and pushing a conduit gromit in between them or holding them (had tested for live) stopped the vibration.
It is not doing it now and nothing else has changed apart from a bulb (Sorry - lamp) which blew (due to handling?) but this has been eliminated because it also buzzed with the lamps out. Holding the light anywhere else did not damp out the vibration.
It is not doing it now and nothing else has changed apart from a bulb (Sorry - lamp) which blew (due to handling?) but this has been eliminated because it also buzzed with the lamps out. Holding the light anywhere else did not damp out the vibration.