I just removed the first roll of film from my Rolleicord V which was wound onto one of my modified spools (see post #12). This exposed roll was easily removed. If the other spools I drilled continue to work as well as this one did, I will consider the problem solved.
Looking closely at the left-side spool knob, when I pull back on that, the entire shaft retracts, and no part remains inside the walls of the camera interior. In other words, in my case, there woud be no benefit in grinding off the end of the left-side shaft. I am convinced that whatever the problem is, the source of the problem is on the right-hand side -- something to do with the winding knob shaft.
As best as I can measure with my old-and-worn Eldi vernier calipers, the round part of my Rolleicord wind knob shaft is 5.5mm in diameter. And the round part of the recess in the end of the spools I have measure 5.1-5.2mm. My theory is, the undersize holes in the plastic spools are gripping the end of the wind knob too tightly.
The 7/32" drill bit I used to enlarge the holes in the spools should make a hole about 0.219-inch or 5.56mm. When I measure the drilled holes, I get a little less than that, 5.4-5.5mm. But as I mentioned, the plastic did not drill cleanly so I may be trying to measure slightly irregular holes. I probably should have used a new bit and reduced the speed of my drill press. But whatever the modified holes may measure, they now work as expected, which is all I care about.
If my assessment of the problem is correct, then solving the problem by modifying the camera would not be a diy process for me. Once the wind knob is removed from the camera, the tabs or "ears" would need to be detached from the shaft (I assume they are removable?). Then I think the shaft part would need to be lathe-turned to reduce the diameter(?) For me, the quick and easy solution is to keep a half-dozen modified film spools available in my camera bag ready for whenever I change film.