A lot of platers will nolonger bothet with Potmetal parts. Because Good pot metal classic parts are becoming very scares amd and pretty much all that's left are parts with pits, broken etc. which are bug problems for chrome shops with regard to their method of repair (soft solder over copper). Bottom line, they just don't want to get involved.
The dark spots are corroding metal (dead metal) those must be spot ground out and filled. And big holes, missing metal are an impossible task for platers. However that's not the case with welding. Pits, Holes, missing metal broken parts are no problem. Dead pot metal is simply replaced with clean pure zamac (pot metal) Maki ng the part(s) easily replatible.
Anyhow, I hope this sheds some light on replating old pot metal..?
Please feel free to contact me directly via DM, email, text message or a call at 7076215052.