Indirectly related: I recently attempted to refurb my 83 PSC 37 bronze port
lights' interior surfaces. The first one I applied Brasso on a rag by hand and carefully buffed to no advantage, then graduated to a toothbrush with no significant improvement. Disgruntled, I detached the hinged window "frame" from the portal and used fine sand paper (did not, but should have had dust mask - very dirty) followed by Brasso for good results. The interior surface of the portal took much effort as it is tedious to work standing leaned over at eye level. Sanding and polishing the small pieces were tedious as well. I finished it off with Never-Dull. Seeking a faster, easier approach on the second one, I again detached the hinged frame from the portal and then disassembled the retaining ring to scrape/remove the old (polysulfide?) black adhesive and pane. The original #? screws are weak and several failed. Replacements not readily found but suspect a clock repair shop may have them. I tapped all and used new #6 brass screws (Kemah Hardware). Re-tap the small holes - do not drill out for #6. Drilled out two stubs - don't. Recommend leaving stubs and drilling/tapping new offset hole thru retaining ring (countersink) and frame - alignment critical - tap both together. Using PPE outdoors I dipped/soaked/rubbed for about 5 minutes all bronze pieces in a plastic pail with a few ounces of muriatic acid for swimming pools ($5). I filled the bucket with water to rinse and then neutralized it to pH > 6 before discharge. Used Brasso to clean up remainder. Applied common silicone directly to edge of pane to seal safety glass. Re-assembled using clear Life Seal ($13/tube - don't over apply). Let it setup some before tightening ring. I covered with plastic/masked off the interior and (with PPE) used a small brush to lightly, sparingly, apply acid from a plastic cup onto the vertical interior surface of the portal. Very delicate and risky. Fumes. But effective. Finished off with Brasso and Never-Dull. Method #1 is less risky but requires more elbow grease and time. Looking for better way.