Originally Posted by mama's place

Not at all an expert on this subject but....advice I read says 1. Change to new sharp needle
2. Clean for lint or threads EVERYWHERE
3. Use the same thread type, weight in top and bobbin
4. Some machines prefer cotton thread
5. Rethread machine maybe you missed one spot..

6. Try changing to a new bobbin...maybe it wasn't wound smoothly Don't give up, you'll find the problem!!
My machine doesn't do a great loop or curve for me but it is better with cotton thread...You'd know I bought a bunch of polyester thread...LOL