@Mojo ideas
and
@Rob Watts
, It's actually not that the round ball is too big. All the balls on this Mojo have play of about 1mm in any direction. They are all free moving, and can be moved as I say 1mm in any direction, left or right. I actually though they were all a bit loose when it arrived. Though I took no more notice.
What worries me stupid, is that the button under the ball does not feel right. It makes no click when pushed. Secondly the action pressing the ball down only goes about half the height of a press down on any other button. However it's not that the ball is holding the button down, because the ball is completely free moving and spins very easily. It's the action on the button underneath is not like with any other Mojo button I have seen. It feels like the button is about to give out, though of course it may not.
What worries me also is resale value too. I would have to go through all this rigmarole of explanation if I sold it. The buyer might think I was selling it because of this reason and want it cheap.