Raziel it’s very easy. 1st make absolutely sure you don’t twist the gauge by the body, if you do there is a great chance of the retaining mechanism between the guts of it and the case snapping off inside. There is a square nut type thing behind the gauge, use that to loosen it with a think spanner, or thin long nose pliers.
Then rewrap the thread in PTFE to it feel tight all the way in and stop when the gauge is in sufficiently (not all the way) and properly aligned