Dim lights in dash

Hundreds of headlights switches have been replaced due to a failed dimmer function.
Its quite simple to install a jumper over that function component. Result is 100% of current regardless where the knob is turned to. The dome lamp function stays intact as well. if this doesn't make the lamps bright as possible, the fault is definitely in the connections from here to chassis ground.
There are only 4 bulbs for illumination in a rally panel. If 1 is burned out you would have a unlit area.
The other 4 are on indicator circuits. Those do utilize the same chassis ground path so if the problem was in that, those bulbs would also be dim. That is Excluding the park brake lamp. it grounds at the switch on the mechanism. If that 1 bulb burns brighter than any other, all others equally dim with the dimmer feature bypassed, the ground path at the inst' panel is suspect.
Sort of a process of elimination diagnosis, before attempting to remove that inst' panel.
Hope it helps