Thread bunching. I have a JcPenney 7050 sewing machine cat number 868-4532 and it is currently

Question

I have a JcPenney 7050 sewing machine cat number 868-4532 and it is currently giving me problems. When I sew the material does not move and all the thread bunches in the bobbin area. Before this new problem it was just bunching the thread on the bottom part of the material. I think I have it threaded right and I have checked the tension which I also think is correct. I have this machine for quite sometime at least 15 years. What could be causing this to happen? Can I fix it or should I think about getting a new machine?