Rant:
Vittoria replaceable valve stems suck!
I'm down to I think the last one of these, a file tread tire used for all around riding on the CX bike. It developed a slow leak, and I thought about adding some goop, but the valve core is not removable.
The leak got worse so I pulled the tire and found no puncture, just the stupid stem having come loose. This is not the first or even the third time I have seen this with various tires.
At least Vittoria finally abandoned the misguided idea, so possibly you have been blissfully unaware- if so, count yourself lucky.
] rant