Instrument cluster problem and identification

[bignslow]

Is there a way to determine if my car has original or correct instrument cluster? It's a 1991 318IS. I noticed my speedometer isn't accurate so I suspect it may not be original.

I also have an issue with my temp gauge where it sticks when cold. First thing in the morning when I start driving the gauge stays cold until I hit top of the dash at which point the needle bounces over to where it should be. Is there a fix?

[Vincenze]

There is a circle with the production date on one of the tabs.

The cluster gets its settings from the front coding plug.
But the speed information comes from the rear differential sensor. It should be the same for all models unless the speedometer is Canadian or European with km.

There can be soldering joint or connector problems on the PCB if the gauge works when you hit it.