My personal feeling is that if they move at all, they are good.... and you can adjust the fuel, oil press, and temp gauges.
they sense resistance to ground. there are set value resistors you can buy from radio shack very cheap. ground each gauge with a wire that is split by these resistors and then adjust the gauges to read properly.

Have you removed, cleaned and disassembled your gauge cluster? before giving my 68 charger gauges a makeover, I had some intermittent issues. I found that just by removing the cluster, taking apart, cleaning, and putting it all back together ended the problems. while they are out, you can make up your rig to test and adjust. very easy to do.
A voltage limiter needs to be plugged into the circuit board. Attach a 12v power source to the circuit board pin that supplies power to the board. Ground the cluster housing.

Go to Radio Shack and buy these resistors.
271-1101 10 ohm
271-1103 23 ohm
271-1109 150 ohm

Just attach a short piece of wire with a small alligator clip on each end to a single 10 ohm and 23 ohm resistor
Take two 150 ohm resistors and put them side by side and then attach the wires with clips.

The jumper wires are so cheap you could make three of each and have all your gauges testing at the same time.

The LOW position is 73 ohms
The MIDDLE position is 23 ohms
The HIGH position is 10 ohms

Temperature gauge
The L position should read 120* on the dial
The M position should read 170*~180* on the dial.
The H position should read 250* on the dial.

Oil gauge
The L position should read 0 psi on the dial.
The M position should read about 30 psi on the dial
The H position should read 80 psi on the dial

Fuel gauge
The L position should read empty on the dial
The M position should read just under 1/2 on the dial
The H position should read full on the dial

look at the attachment..on the back of the gauges are two little round "windows" inside each is a 'wheel' that you can turn to adjust the sweep of the gauge.