Sr20 core plug reseat/replace

Hey guys, long time since i posted. Been cracking on with the 14 and just keep finding issues where ever im led with the tools.

So chasing an oil leak that i thought was from the oil pressure sensor switch, turns out, it might be the rubber core plug on the block?
1. Can this be removed and reseated? Or if this is removed, will it drop something internally? Im trying really hard to not split the engine as its quite healthy and a bit pointless at the moment.
2. Can it also be reused or would it be safer to just replace for new?

Tia

Just for info as no one seems to know, its a threaded bolt, with a copper washer. Im still yet to find out the size of the washer, but will get measuring soon.
It also had some factory sealant on it, which had been damaged from the bottom and was leaking slightly. Its not oil, this is a water jacket. so back to the drawing board for me.

if the washer is still structurally sound then you can just reuse it. maybe anneal it first. the sealer will either be liquid ptfe or threadlock.