[Chuck Schwark]

Shadow Meters have a permanent magnet in there to "bias" the vane to the neutral position and it's likely weakened over time and the current thru the coil is not enough to cause enough swing. Also very important is the accurate IF and RF alignment to maximize the resulting AVC voltage (and RF tube plate/screen current draw thru meter coil and vane movement) to make the set perform to it design max. If possible, a better aerial and ground system will also help to bring in more signal.

Chucl