Take them out and give them a good cleaning and inspection. Be very careful with the tube connected to the temp gauge, it is gas filled and if you break it it will never work again. The gas and amp gauges will most likely just have bad connections or broken wires somewhere. If you want new gauges then you can get them from Jim Carter or American Classic see the links on the home page of stovebolt.

1953 Chevrolet 3600
Fried Green T'mater (Vern)
In the Stovebolt Gallery
Caution: Political Statement
Man who runs in front of car gets tired, man who runs behind car gets exhausted.