I went to see a Tiegel black ball today. It wouldn't register. Our press is a "red ball" meaning that you are able to lock the ink rollers up while the press runs. Very handy for inking just the drum for a test color or run. Very tedious with always moving rollers.
For a windmill to print in registration, a whole lot of things have to go right but here's a simple one that can go wrong that can easily be avoided. Remember that the type of guides dictates the physical placement of the feed stack. If they're nickel guides, the stack has to go pretty much hard left. If brass, less so.
You know that gauge down on the lower left of the press? Slide one way for nickel the other for brass. Set it, tighten it down and then push your left side stack standard against it.
Remember that when the gripper arm opens to release the paper to the guide bar, the paper should not "drop" any real distance to the bar. It should pretty much transfer to the bar simultaneously with the gripper release.
Put the paper too far to the right in the feed pile, you can have paper falling 1/4 inch, more than enough to cause no registration, paper falling out of the platen and other annoying and expensive problems.
Check your stack.
Here's another thought. If you making Rube Goldberg type "adjustments" to your feed stack, or just about any other part of your Windmill in order for it to print properly, you are doing something fundamentally wrong. The machine is just about perfectly designed just as it is. RTFM.