I bought a used Hustler stainless steel ball mount with a spring at a
recent hamfest. I installed it with a stainless steel Quick-Disconnect
(QD2) screwed into the top of the spring. I found that the spring was
extremely weak, and suspect it is not the original spring from Hustler.

I removed the spring and attempted to screw the bottom piece of the QD2
into the ball mount. It started OK, but wouldn't quite screw all the
way in. Then when trying to remove it, it came out about half way and
seized-up. I'm sure it wasn't cross-threaded to begin with, since it
went in several turns without using the wrench.

Although it was hard to turn, I persisted until the QD2 started to turn
more easily. Then I realized that the piece it was screwed into was
also turning!

Does anyone have any suggestions on how to undo the seized parts?
(Penetrating oil and freezing the parts didn't make any difference.)

Fred
K4DII