Those look like Waterway jets... which I have in my tub. The "internal" is most likely stuck. If you turn it counter-clockwise, it should break loose, rising out of the body 1/4 to 1/2 inch or so, then just pull it out. Saw a spa tech use a pair of channel locks on a jet once, because it was so bound up in the body.
If its been there for a long time, mineral build up can really make them a bear to remove.
Some of mine fit loosely enough to simply pull out, others I really have to crank them left, to get them out of the bodies.
I guess its possible to break it off in the body, but it would REALLY have to be bound up with gunk for that to happen... in which case, you may want to get it out of there and replace it anyway.
Nice tub, btw.
