Jon I ve had that too and it was a Chinese one, must be there tolerances.
It's most likely someone in this country would have commissioned a Chinese company to make these for a fast buck! rather than a Chinese company starting up with a long term plan to supply these worldwide if it were the latter they might stamp their name to it have pride in the quality of their product and a longer term view.
Chinese need to learn to make decent stuff instead of a fast buck!
Dont get me started on the motor bikes they are making!