I honestly think the 510 on the KFL isn't the real issue , if you used the Magma on the MVP you've probably forced the center pin down on the MVP , I have to readjust the center pin on my Panzer following use of the Magma on it to get anything else to work , it's worth a try to pry it up first , it will take a month shipping both ways if FT issues a return ticket for the KFL base and you're likely to have the issue with the replacement .
I think it's a combination issue. His KFL pin is a bit too short AND his other devices centre pins are a bit pushed in. Yes, prying the centre pins up on the devices should work but I can tell you this much about my experience with the cheapo 510 pins that they have in most devices, once they start twitching and moving, they're pretty much done!
