Hello John,
I take it that the needle is not picking up the thread from the bobbin, very important and may sound obvious but put a new needle in and make sure the needle is in the correct way round, if you can't pick the thread up from the bobbin then the chances are the machine is out of time and will need retiming, you can do this yourself but you must have patience because you may not get it right first time, try the above first and get back to me on my e-mail and I will help you retime the machine.
Ken
drivewithken@blueyonder.co.uk, September 2007