For some people, vision center placement isn't as critical as it is with others (i.e., some people can accurately perceive the line of the shot and cue alignment over a range of head positions); but for most people, in my experience, a small change in head alignment and orientation can make a huge difference.Thanks Dave. I bought Tucker's 3rd Eye Trainer a while ago, and have tried other "at the table" methods.
The same issue would always arise. One day I could play a perfect center axis stop shot and the cue would be under my left eye. The next day I could do it under my right eye or directly under my chin. It was never consistent for me, and I imagine it has something to do with subconscious making the corrections.
When you do the at-the-table tests, be sure to try different head positions to visualize and test the differences.
Good luck,
Dave