I suspected broken ribbons.  It could however be something else, so the camera had to be stripped to see what really happened..  Getting the Canon P out of its shell was surprisingly easy

Removing the four main screws on the outer shell, the selftimer lever assembly, the lens mount, and a couple more screws under it, will take the shell off.

One of the ribbons which pulled the second blind home had snapped.

Titanium foil was used by Canon for their model “P” and “7″ RFs, in place of the usual rubber-coated cloth.  The titanium foil can wrinkle from fatigue.  Or in this case, stress from being stuck and then being pulled out to be mended.

The top of the camera is very complicated.  This scary looking part has the shutter speed controls, the wind/rewind clutch, frame counter, shutter release, and film advance/transport.

And this is the part which gives the floating framelines.  It’s semi-silvered inside.

The broken ribbon was replaced with a new one.  The intact upper ribbon was unglued so that a new one can be patterned after it.  The shutter was no longer disassembled.  The ribbons were threaded through the rollers, attached to the lath, and the other end reglued to the outer roller. Stitched in red:

Under the camera is the complicated Canon RF flash sync circuit.  Disassembly not recommended!