Fuel injector seized

[mblack]

Hello all,

I'm in the process of removing fuel injectors and two came free without issue, snapped free and spun out with fingers. The other two are seizing after I turn them about 1/16 of a turn. They do not snap loose like the other two. I'm thinking either carbon deposits at the base of the injector or the aluminum was partially stripped at some point. I am being reasonably cautious to avoid stripping the head threads. Presently have penetrating oil sitting on them, have used a dentist pick to get rid of all the crud at the base.

Any ideas?

Thanks,
Matt