Ok, do you mean the hex slot for the stud is stripped or the insert in the body has come loose from the mechanical pressure of strings/springs?
If it's just a stripped hex slot in the stud, you should be able to buy a TRS type replacement quite easily, they're common and not that expensive.
If the insert in the body has come loose, there's a couple of ways of dealing with it. This happens on some basswood guitars, particularly with recessed trems which tend to have shorter studs/inserts, so the pressure of the strings/springs is more focused near the top of the body. Because TRS studs aren't locking, there's a bit of play between the stud and insert, which, over time with trem use, can result in the insert leaning forward towards the neck and being worked loose (I had an RG320 once, similar to yours, which developed such a lean on the treble side).
A quick fix is removing the insert in question, rebuilding the enlarged hole with wood/glue and refitting the insert so it's a tight fit again. A more labour intensive variant of this is plugging the hole with a dowel and redrilling.
If you really love the guitar, you could change the whole trem assembly. The Gotoh GE1996T is often recommended here as a replacement as no modification of the cavity is required, though you'd have to enlarge the holes for the inserts, as the Gotoh ones are longer and have a slightly bigger diameter than stock.
Yes, the studs are threaded, so the usual righty tighty, lefty loosey applies and they can be removed by hand when your bridge is off. The hex slot is there to make finer adjustments when the bridge is all set up.