Nothing has been knocked out of alignment.
I took careful measurements when I removed the presser bar to make sure I put it back exactly as it was before.
There is no way to mess up the alignment of the presser bar, because it rides in a vertical hole machined into the casing.
The only possible way to screw it up would be the height and rotation of the bar, because it is a featureless rod held in with set screws.
I scribed witness marks onto the bar to ensure that I could put it back at exactly the same height and attitude as it was originally.
The problem was caused by the fact that high shank and low shank are NOT the same except for the height of the shank.
It's all over the internet that they are the same except for height, and you have repeated it here, but this is NOT true.
If you don't believe me, look at the alignment of the needle bar and the presser bar on both a high shank machine and a low shank machine.
Rodney verified this for me by examining one of his low shank machines.
The distance between the needle bar and the presser bar on the low shank machine is smaller than that on the high shank (6mm vs 9mm) which is why the slot on the zigzag foot was too far forward (by 3mm) when I tried it.
Furthermore, the presser bar is slightly to one side of the needle bar on the low shank, whereas they are aligned straight on the high shank.
This is why the presser foot was shifted slightly to the right.
Presumably these differences are taken into account in the design of the adapters/shapes of the ankles.
I have replaced the original low shank foot that came with the machine, and it is perfectly aligned.