I had shredding problems off and on for a couple of months. Changed the needle, thread, rethreaded, oiled, cleaned, used a diff bobbin...called tech support. Christmas happened, then a trip to my parents, then the flu. FINALLY got back into the sewing room...shred. Talked to my dealer at a show and the owner of my long arm company was there. He offered to come to my house. Guess what it was? a HUGE blob of oily lint...lurking on the bobbin case housing ...as it turns..it was wedged up in there. Took HIM 20 mins to find it. I suggest a diff bobbin, and a good session of cleaning..and maybe an extra drop of oil. I have found that blob there again, but NOW I know to trouble shoot there. Another lesson on my troubleshooting list! Good luck on your search...