Originally Posted by
fietsbob
May have to open it up and deal with the innards..
Dunk clean it, re grease, and put it back together?
All else, get another hub just like it,
then you won't have to respoke the wheel., and swap cores..
....
Cleaning and re-greasing it is. Hoping it will solve the problem.
At the risk of appearing stupid:
The swapping cores thing. The hub is already laced to a new rim. It's not a problem doing it again with a new hub - I'd rather do that than re-use the old, faulty one, even if it's just swapping the innards. Unless Shimano "skimps" on grease with gear hubs - in that case, overhaul of the new one is needed anyway, so I might just swap the inner parts.
EDIT: The only other thing that comes to mind is loosening the (locknut) preload a bit - see if there's room to do that without causing play and see if that helps.