[Chuck Schwark]

Remember, the shadow meter responds to RF and IF tube plate current fluctuations due to being tuned on-staion and off station signal strengths. The better the set is aligned, the greater the AVC voltage that influences the grid bias on those tubes and subsequently the plate current draw on the B+ line through the shadow meter (in the B+ line). Depending on the strength of the bias magnet in the about all you can ask of a 60-70 year old permanent ring (C-shaped) magnet in the shadow meter.

DO NOT EVER SPRAY WD-40 IN THERE. Maybe a teeny-tiny drop of watch oil - very light type at the pivot points.
Usually you don't have to lube at all, unless there was corrosion at the pivot points and subsequenly cleaned. If the pivot holes are good,
I woul not lube at all, if it's freely moving with a puff of air.

Chuck