75 Duster Tetnus Shot and band aids

I started working on a instrument cluster out of my parts car. The pieces were broken off the bezel but still attached to the metal gauge cluster piece Luckily the screws held the pieces to the metal frame. I need to get some of those plastic sheets for the other broken parts The metal part of the cluster has corrosion Do the gauges use the metal frame as a ground? I would like to just paint the whole metal frame and not just the inside of it