IMHO, ya'll still have not got to the root of the problem. When I worked at a sewing machine store, the repairman would laugh when customers came in after having their machine fixed or tuned up, with their sewing machine not working again. I soon learned why! He told me NOT to tell, but, being honest always won out! When the customer got the machine to the car, they would check it to see if it sewed. BUT, they did not lower the presser foot with cloth underneath and lower the needle back into the cloth. Next, they would hurriedly throw the machine into the car or trunk. This could possible knock the TIMING OFF! The needle bar, feeddogs and the presser foot MUST be timed in synch to sew correctly.