Are you threading with the needle up? Also try grabbing both bobbin and top threads when starting a seam.
Regardless of design - I've had the top thread pop out of the take up lever. In machine embroidery, the problem is often the opposite side. If you have a rat's nest underneath, the problem is usually on the top somewhere.
With the bobbin - check to make sure it's securely in there. The new Ambition is drop-in bobbin isn't it? Those who use drop-in bobbins might have more suggestions.
I've got vertical bobbins and they don't always catch on the spindle and pop out. There used to be a good click on the older Pfaffs, not so now.
The older Pfaffs had lousy thread cutters. A lot of times they will NOT pick up the bobbin thread correctly or at all. However, with a drop-in bobbin the thread cutter should have improved.
Last edited by Weezy Rider; 09-25-2012 at 05:28 AM.