I had this problem in an 85 Fiero after I swapped the dash. After pulling the dash to check all my connections and failing I found some of the pins that went into the cluster were more smushed in than others. I cleaned all the connections with baking soda and a toothbrush and used a small flathead screwdriver to push them back out and my dead gauges worked again. Although on my 79 Grand Prix when I turned on the headlights everything went flat and I never figured that out.