Do NOT use an ohmmeter to measure across the meter. The ohmmeter current could injure the meter movement.
Measure the voltage across the meter. As this increases, the deflection of the meter should increase correspondingly.
Sometimes the tiny bearings that the meter movement swings on get sticky. One cause of this is the lamps that backlight the meters. The lamp generates heat. The heat warps the plastic housing on the meter movement. The warped housing puts stresses on the movement. This deforms the movement ever so slightly -- and this leads to a sticky movement.
The meter draws very little current, so, if the selector switch has been deoxed, it's unlikely that the switch contacts are damaged.
On most Marantz receivers, meter deflection is adjustable via a trimpot located on the AM/FM tuner pcb. Occasionally the trimpots get touchy or open. You can determine which trimpot is the right one by monitoring the voltage to the various trimpots while tuning into and out of a station. The right trimpot will show a rise in voltage as you tune in and a drop as you tune away.
A majority of faulty trimpots can be repaired by deox treatment.
Often the meter drive circuit employs a capacitor as an integrator. Put simply, the capacitor makes the movement respond only to slow changes in signal strength. If this capacitor goes bad, it can cause misoperation of the meter drive circuit.
Hope this information helps.
Fred Longworth