many thanks Eric

I'll be trying this when I get back to where I have the seats. I'm trying to remove the additional hardware from intact (not disassembled) seat backs - the vinyl covers and foam are in place. Is this possible or do I have to remove everything?

"With the plastic nut removed, push the metal tube up and then out of the black plastic bushing while pushing down slightly on the black plastic bushing."

By black plastic nut, do you mean the knurled nut that you tighten to adjust the height of the headrest?

In order to push the metal tube up, does the vinyl and foam have to be removed?

"Then from the underside of the metal bracket, gently squeeze the 4 flexible fingers on the end of the black plastic bushing while pulling up on the top of the black plastic bushing."

From the sound of this, the seat cover and foam have to be removed to gain access to the bottom end of the black plastic bushing. Am I wrong?