White jeans model 1899: I adjusted the tension and it froze up?

I was sewing and I adjusted the tension because I kept hearing the bobbin clicking. The bobbin thread kept getting bunched up and the needle wouldn't move. So twice I cleared out the thread and fabric re threaded both bobbin and needle and the darn thing froze again. I re adjusted the tension to 0 and the machine worked. I then adjusted it to universal and it permanantly froze. Bobbin winder works great but machine will not sew. I took the whole darn thing apart and still can't figure it out! Please help!!