Correct, the split images did not align. They were noticably off. The sense was that the focusing ring would have needed to turn a little further beyond its infinity stop in order to bring them into proper alignment.
The recalibration was pretty standard. Underneath the hotshoe mount there are three visible adjustment screw heads. The one on the right sits higher than the other two. I adjusted the middle set screw until the hospital images were perfectly horizontally aligned. Meaning, when I rotated focus to the infinity stop, the vertical lines of the building clearly snapped into sharp alignment.
Getting to these screws can be a bit baffling the first time. One must first slide the flat silver spring tensioner plate off toward the rear. There is a microscopically small pry-off slot in the front edge of the circular black plastic piece that contains the round metal flash contact. A very small, flat jeweler's screwdriver blade is needed to initially lift the tensioner plate for removal by sliding it over that contact. After that, it's pretty obvious, with four small Phillips head screws holding the shoe itself to the top plate. Once the shoe is removed, the adjustment screws inside the top plate will be easily seen.
If you try this, a few words of caution. You will need a very small diameter extended screwdriver blade to reach the adjustment set screw. I had to purchase a separate precision set just to find one with a long enough reach. It must also be very narrow, otherwise you can't also see into the hole to properly set the blade.
And once properly set into the screw head slot, you must be careful not to press down with any force. Although I can't see the entire mechanism through the hotshoe, my sense has been that this adjustment screw seems to itself be located on a moving part. I could be wrong, but that's how it feels. I've noticed that if I press down even slightly, without even rotating he screw itself, the patch alignment is severely altered. Usually for the worse.
It's a very delicate adjustment. At least for me. Once you get close, it then becomes a series of gentle trial-and-error final attempts until you finally hit that perfect alignment.
Hope this helps.
[Edit: If anyone else out there has also attempted to adjust their own GF670 rangefinder, I'd love to hear your details. Especially any knowledge as to whether those set screws are indeed mounted on moving parts.]