Thanks, John! Can't tell you how much I appreciate your help. I tried inserting the tube and it fit just fine. It did separate the terminals a bit, though not much. Just to play it safe, I detached the wires (was worried I wouldn't be able to) and reattached them, making sure to leave more of a gap. Spacing looks closer to the manual now. I was a little afraid I'd bend those socket terminals if I crimped them real tight, but so far so good. On to the next step!
-Jonathan