Autometer electrical speedo meter broken?

[Moabdude]

I have a covan dash with Autometer gauges.
Sometimes the Speedometer works, sometimes it doesn't. How come?
If I turn on the ignition the needle goes up and after 2 seconds it goes down. Than I start the car. Lately it fails 2 out of 3 times. is the procedure not good?

Also the oil pressure gauge and temperature gauge have problems. Sometimes they work, sometimes the don't but all independent from each other.

first think you would say is: ground.........
thats not it.

please help!