The tubes shifted a tad towards the head, with too much of a gap to fill in since the tubes are only 16ga (0.050") thick. This is the #8 primary:
The #7 that snakes in between two other tubes was easily fixable; I just sliced the previous weld and added a short section to bring the final weld joint back into alignment. The #8 was trickier, because there was no such previous weld joint that I could easily
add onto to bring that misalignment back in place. So what I noticed was this (mocked up with two other pipes):
I had two tubes with non-coinciding centerlines. If I could make a small "slanted" tube to take up the misalignment where that red parallelogram is drawn, but not so slanted that it makes for a rough transition, everything would be nice and dandy. So I went to work. With math.
Since the tube centerlines were parallel and non-skew, all I needed was the angle from the vertical, shown in purple here:
Since those blue dashed lines are essentially parallel, if I know the purple angle inside the green triangle, I automatically know the other purple angle that slants from the vertical so I can set up my metal chop saw right away without guessing.
Here you can see the approx measurements. The centerlines were off about a tenth of an inch, and I wanted to make the new slant approx. 0.42". This was as far as I could go because then the tube curves upward, so this is as smooth as a transition that I could afford. Here you can see where I easily figured out the amount I needed to slant cut some pipe:
So 13° later, I had this piece. No guesswork, no need for eyeballing, etc.
Lo' and behold, it fits darn near almost perfectly.
Prepped for final welding:
Dinner calls now, so I'll stop here for today. Final pics coming soon.