Hi, I did indeed figure it out. Firstly, I wouldn't judge the alignment of the front standard (can I call it that?) by eye. On my example it never looked perfectly parallel to the body/case despite producing perfectly sharp photos (with caveat below). Only way to tell is to shoot a test roll, or rig up some ground glass and inspect with a loupe with the shutter open.
But to answer your question, the issue that plagued my Plaubel Makina 670 was that the springs responsible for locking the front standard into place once extended never quite did their job properly, even after replacement. Many times I would extend the bellows and I would feel the click of the front standard locking into place, but it wasn't fully locked: there remained a millimeter or two of play in the bottom lazy tongs, which of course would throw the top half of my frames out of focus to varying degrees. I learned that if I extended the lens all the way to the minimum focusing distance and then pulled a little, I could get the lazy tongs to properly lock and the camera would produce produce wonderful looking images.
That was of course until the film advance slipped and jammed, and then I dropped it packing it up for its 4th trip to Mr. Binder (wizcam) and split the case open.

I sold it for parts and moved to the Mamiya 6 system.
Anyway, long story short, check the front standard for any slop/play/wobble when the bellows is fully extended. There should be none.
Good luck!