Fuel gauge and water temp gauge not working

[pkinna]

I have a 1991 Ford Ranger, 3.0L
The fuel gauge hasn't been working for some time. I have just been using the odometer., but lately I noticed that the water temp gauge now is not working. (they sit side by side on left side of instrument cluster)
I pulled the instrument cluster off and cleaned the contacts, but still not working.

How do I test to see if the gauges are at fault or it is something else?
What contacts do I short or what points do I test?
Could it be a common wire? If so, where?

thanks for the help...