Well, the good news is I was able to disassemble the gun as per the video. And I cleaned some gunk out in various spots and I found a couple of screws that were not tight at all. When I reassembled them I tightened them. Not blood tight but tight.
And now for the bad news....no improvement. Problem still exists on 2 chambers only.
I can get the hammer to full cock by moving the trigger forward as I'm cocking the hammer, as was suggested by Hawg.
That's where I'm at currently.