If the motor is turning but the blades are not then I would say that something has happened to the drive cams. In the past I have found drive parts (when available) to be costly making repair uneconomical. It is probably worth stripping trimmer down in a hope its just a pin etc broken but often it is best to pop to say Argos and get a new one with a nice 12month warranty.
Robin S
August 2008
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix hedge trimmers.