Instrument bulb lighting...still dim

There are several things that contribute to dim instrument bulbs. Most common first efforts are headlight swich and bulbs. Not all panels are the same so I'll guess your isa metal insrument housing with lamp sockets attached to a circuit board. Lamps position has a screw attaches the circuit board. These screws are also one of serveral pieces of the ground path. Its more like a chain than a wire. For this clean to conduct current like a wire, every link must be well connected.
The very best solution is to install an actual ground wire.