Yesterday, I have restored the second auxiliary light...

The rust has to be removed as well as the brown varnish under the chrome. Then get a nice bare metal finish with a 400 grid wet sand paper.
Using the Eastwood zinc plating kit, I filled the optical lens up to the rim and gave it 20 to 30 mn process.

After plating...

I used steel wool and Autosol to get the final finish.

Much improved...


Some rust inhibitor to treat and protect the back side.