I found a 2mm pin and made a ballnose on tip. Functioned exactly what you did with dremel diamond 2mm ball but I "lapped=polished" the diamond compound into the 2mm pocket (black delrin piece) by hand only turning the pin between fingers.
Now the 2mm ball fits the pocket perfect, you will see you have eliminated the creep for a good.
Also, the other method was - remove the Reg core (pin and washers), screw back all together and pressure the tank. Because there is a pressure on one side only it will push the 2mm ball into the hole/pocket, leaving it like that overnight the ceramic ball will push=nest itself into that "seal".