These Jideco motors have been built with new original equipment brush holders.  Armatures are cleaned with a three step process to ensure they pass noise inspection. Motor tails are either gold or sliver, some tarnish on them may be present.  Send back your core for an exchange, I will only take Jideco genuine motors as a core.  You will have to send it to shop address on box or ask for address and there is no time limt on exchange.  Reset tips and help line available if you need it.