This is a real instrument. Don says it is not the right one for an A-4.

[9/19/2019] Disassembled it, removing the portion which senses atmospheric pressure.

On the face, there is a small motor and flag which says “Code Off.” With trial and error, discovered it will move by applying 12VDC directly, drawing about 47 mA. It won't move at less voltage, tested with 5V and 9V.

It appears I broke the needle shaft off, although it looks clean under a microscope. May be able to drill out the shaft and replace, not sure.