Last link is good for removing the top cover.
In your case I would remove only the focusing ring and take a look.
When taking it out.
You will see two pins, outside pin marks the limits for infinity and close focusing. Inner pin moves the rangefinder cam.
What I think it happened it’s the inner ring got loose, check the small headless screw that tights two rings together. That screw is on the side if the focusing ring.
From there if the camera didn’t receive any bump the configuration of mirror/beam splitter should be fine and it’s a matter of setting up the focusing ring with the inner pin correctly at infinity with images matching. You can move inner cam with a screwdriver and set the images in advance and then put the focusing ring matching the pins and locking the headless screw back.
I hope it was clear, otherwise someone should clarify my instructions