I had the same problem, seems the battery is fine as I have a lamp which still works from the same type.
Took the thing apart and the motor still works.
What seems to have happened on mine is that the trigger/switch has broken, have tried to source a new one and found the manufacturer http://www.jiaben.com/en/pro_show.asp?id=263 and the part, but there doesn't seem to be a UK importer.
Any ideas?
Mike Pears
November 2009