I don't own a MVP but want to make sure I understand what you mean.... the 510 conn has a coating on it that is rubbing off on the base of the kayfun? I also do not understand what you meant about "move the build". Can you elaborate? I'm sure someone will jump in or perhaps you could start a new thread in a section where more MVP owners might see it. Sorry -- I know this was not much help.
Yes, as you can see in the pictures, that base in the MVP is basically just all silver, as you can now see it's got bits of this brassy color because the kayfun is chewing on it whenever I put it in and when I clean that connection on the MVP with cotton, well you can see all the silver/metallic crap that is pretty much scaring me as Im afraid I might be inhaling that?
Basically, if I try to tighten the connector screw on the kayfun, which is what's causing this as it's not flush with the tube where that screw is, the positive build area moves to the side, it literally moves, I saw Pbusardo talk about this, the Russian does not do that. So basically, that screw is sticking out a bit and hence chewing off the connection on the MVP.