I am convinced that on this Graphex-X I've been working on is suffering from a completely different problem than the cam that I actually addressed. As I was rebuilding the shutter I noticed upon inspection that the bushing in the main lever assembly was scored, and that the post it turns on was worn down and scored. The best analogy would be "ring ridge" in a worn gasoline engine. Because of this wear, the main lever assembly is allowed to "cock", or bind under the intense spring pressure. This binding of course, causing slowed shutter speed. So in essence, I only addressed the problem and not the cause. But even if I had the tools and resources to fabricate a new main lever bushing, it would be of little good because the post it rides on would still be worn and uneven. There comes a time when a device is so worn out that repairs are to be considered temporary. This worn condition explains in my mind why achieving the 400 speed would be impossible. By then, the booster spring, along with the regular 2 other springs causes such a bind that it's a wonder it could move at all.
All in all, a temporary repair, but at age 56, anything is temporary to me. I , myself, am getting more temporary quick.