These are all amazing insights! Thanks! The DIY Duco techniques is something I will try in a near futur, for sure...I finally chose to keep the paint as is and just add a few coats of lacquer (+wet sand). I fixed the interior shell with some glue in the spots where the reinforcement rings were starting to come loose. Now it sings again!I'm happy with the result! Next time, I'll try to repaint it in duco, but I'll have to practice on a cheaper shell before...
A total disassemble and re-assemble usually makes a drum sing again. Were the wires original ?