The top thread is loose and the bobbin thread is pulling the top thread down
Always thread the machine with the presser foot up and see if this eliminates the problem.
Sounds opposite of the problem, but it is very important to do this to assure the tension control can keep the top thread at the correct tension to form a proper stitch.
If the machine is threaded with the presser foot down, the tension control is closed and the thread cannot seat into the control as it should.
Answers & Comments
The top thread is loose and the bobbin thread is pulling the top thread down
Always thread the machine with the presser foot up and see if this eliminates the problem.
Sounds opposite of the problem, but it is very important to do this to assure the tension control can keep the top thread at the correct tension to form a proper stitch.
If the machine is threaded with the presser foot down, the tension control is closed and the thread cannot seat into the control as it should.