I know there was some talk about rhodium plating not being able to be done by a jeweler.
I can't say one way or the other, but I found this on the atmizoo website.
"One last thing to keep in mind is this – if the damage on the contacts is excessive, then polishing them will not be a long term solution, since the silver-plating layer will be damaged. You can tell if the plating layer is intact by closely looking at the polished contacts: If the black areas have a more localized, bright yellow tint after the cleaning, then it means that the plating layer has been damaged, leaving the brass core exposed. You can still twist the fixed hex contacts, in order to get a fresh side pointing up, however, if the moving contact rod is in a similar condition, it might be a good idea to get the contacts re-plated. Take them to your local jeweller’s and ask for a thick silver or -better- rhodium plating***, and the device will be like new again. One more reason to love mech switches.
* Don’t use gold, since it’s only suitable as a dry (non-arcing) contact plating material in low-power circuits."