Yammie

My thought is that your needle isn't big enough. Try a size 18.

Shemjo

This is difficult. Try a fresh bobbin. New needle, in correctly, sometimes mine is backwards! Rethread the machine. Make sure the walking foot is installed correctly, with the little arm over the screw thing. LOWER YOUR PRESSURE FOOT. Take a deep breath, and go slowly. And if that doesn't work, hand tie the dern thing and try again on something when you have lots of time. Most of my problems come when I try to rush things.! :?

hokieappmom

I have a newer Bernina and although I have sewn a lot, I haven't machine quilted much. This was my problem and so easy to fix. I wasn't bringing the lower thread through all the material to the top. To do this, hold your needle thread with some slight tension. As the needle goes through the fabric, keep holding the thread, pulling slightly to bring the bobbin thread through.

rannyof3

YOU MIGHT NEED A HEAVIER NEEDLE.....

nativetexan

free motion sitching then is what you are doing. put the needle down, then up to bring up the bobbin thread. take a few stitches to lock the threads, then begin your echoing. then stop and trim the top and bobbin thread so they won't be in your way later. continue. that should do it.
the bobbin thread will lump up if not brought to the top.
good luck.