I agree - leave the clear coat. It is probably catalyzed.
I have a PSC Pullman with corrosion under the clear coat. I have tried lacquer thinner, paint remover, MEK, nothing works.
When I paint bare brass, I give it a very light bead blast at below 35 psi, with the gun at a 45 degree angle. Blow the beads off, and immediately prime. Then Scale Coat gloss, baked on for an hour at around 180 degrees.