Kenmore Feed Dog FAIL -- What am I doing wrong? (With UPDATES)

Friends, if you watched yesterday's vlog, you know I've been doing some long-delayed maintenance on my beloved Kenmore 158.141, my go-to vintage zigzagger.





I picked this machine up at the Chelsea flea market three years ago and paid $25 for her with the table.  Since that time she has worked flawlessly and I use her (him? it?)  for practically everything.  The one issue I've had since I brought her home, however, is that I can't get her feed dogs to drop.  The mechanism seems stuck.

I was buying something minor on Amazon last week and needed to spend $35 to qualify for free shipping.  I'd had Liquid Wrench on my wishlist for more than a year precisely for the purpose of unsticking this feed dog mechanism, but never acted on it.  Now the time seemed right and I am now the proud owner of a small can of this toxic, stinky penetrating oil.



But I haven't been able to free the mechanism.

This is the switch (below).  When I unscrew the bar that attaches to the feed-dog drop on the underside of the machine, it moves freely.



This is the bar in question.  I removed the screw to have better access to the mechanism immediately to the left.





I sprayed some Liquid Wrench in that cylinder and left it overnight. It doesn't seem to have loosened anything.  BTW, what's that wire passing through it (below) -- is that the culprit?  What purpose does that wire serve?  Does it need to be removed?

WHAT is that paper-fastener-looking wire for?

The other end of the cylinder is pointed (conical).  I'm assuming that the black bar is supposed to pull that pointed cylinder out so that the feed dogs remain in the down position.

Needless to say, there's nothing about how this is supposed to work in the owner's manual.





So what do you think?  Am I doing something wrong, or is there something obvious I've missed?

To be clear, I have plenty of other machines to make buttonholes with.  I do not need the feed dogs on this machine to drop.  I just WANT to make it work!

Thanks for your insights!

UPDATE:  I GOT IT UNSTUCK!  I used my portable hairdryer (which I'd bought used a long time ago for just this kind of thing) for a few minutes and repeatedly knocked on the pointed end with the head of a pair of pliers (I couldn't fit a hammer in the space) and slowly but surely I got it moving freely.  I then oiled it liberally.  Thanks so much for all your help!

Special shout out to Paula W. for getting me photos of her (very similar) Kenmore in both up and down positions (from below).