If you remove the lens, turn the camera upside down, you'll see a round metal disk- this is the rangefinder coupling. surrounding it is a serrated metal sheet. The lens is hitting this metal sheet. You can put a finger inside and press lightly on the metal sheet- BEHIND THE RANGEFINDER COUPLING! Do not press the rangefinder disk. Press lightly and see if you can reshape the metal sheet slightly upwards and out of the way.
You can open the back and lock the shutter open on B (cable release with lock is safest) and see where the rubbing is happened with the lens mounted. Also set the lens to closest focus- fully extended- screw onto the body and then slowly move focus to infinity. This pulls to rear bulb back and might show you that you only need to reshape a small section.