"Jim Burns" writes:

The plug only sticks out 1 thread. It's been painted over, and from
scraping the paint off, it looks like pipe dope in the thread. I haven't
tried valve grinding compound yet, maybe a combination of heat and compound
with a new oxide hex key with a ratchet will work.

Motorcycle people have many of the those plugs to deal with & swear
by the hand-impact drivers; you preload them with a twist and hit
it with a hammer. The hammer keeps the key deeply seated.

Buy a 1/2" square drive key from Snap-on or such.

I concur with the preheating but also suggest getting some Kroil
Oil from Kano labs. It makes Liquid Wrench look like mouse milk.
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