I had the same problem. The holder that the bobbin sits in, oscillates back and forth in normal operation. Looking at another machine it seems the point on the bobbin holder should reach the tip of the needle when the needle is at its lowest point. Mine didn't reach by about 5mm from the needle tip and I assume it had gone out of adjustment so that the point of the bobbin holder doesn't reach the needle to pick up the thread.
Disconnect the power lead. If you look under the machine and remove the cover plate you will find the shaft that drives the bobbin holder back and forth. On that shaft, at the opposite end of the shaft to the bobbin gear, you will find and allen screw and a larger normal screw. I loosened the allen screw, then rotated the motor so you can then loosen the larger screw. Once loosened then, with the needle at the lowest point, turn the bobbin gear so that the point on bobbin housing reaches the bottom of the needle. Tighten the two screws, tight. Re-thread the machine, rotate the machine by hand and check that the needle picks up the bobbin thread.
Peter
February 2012
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