We organized a meeting with internal technical team and reviewed this issue this afternoon:
First of all from design's review, we designed a very small gap between the cup OD and body ID so it will look the best aesthetically; (OD=outer diameter; ID=Inner diameter)
With the minimized gap, it will request the filling accuracy, the lead will always needed to be centralized.
Indeed the cup will slightly off the center during the rotating process, seem it is hard to avoid that with the current construction, our internal team will measure more to confirm if there has any improvement we can do or new construction is needed to avoid that 100%?
Or can we suggest to decrease the ID of the cup to improve this issue? If you are OK, we can build a new smaller ID Cup tooling cores for you?
Thanks for your comments for above.