Can Armoutex remove a seized stem before powder coating?

if the stem is stuck, sound like the metal bit that grip the inside wedged stuck, screw the bolt back, while leaving a handful of space and then gently try and hit it with a mallet, see if that help.

Tried doing that, WD40, freezing. The adjuster bolt came out as soon as I unscrewed it no problem. The stem is actually fused to the stearer tube through corrosion. I promise, it's a bigger job than knocking it with a mallet!