If the stitching on top is rough or frays, one of these issues may be the root of the problem.
The bobbin needs to be tensioned correctly for stitching to come out correctly.
The bobbin may be bent or damaged and need replacement.
If the needle is bent, broken, or dull, the machine will stitch incorrectly. You may need to replace the needle.
If your fabric is getting ruffled or bunched while feeding through the machine, one of these issues may be the cause.
The lowering mechanism provides compression to the presser foot. If your presser foot is not lowering completely and evenly, you may need to replace the presser foot lowering mechanism.
The presser foot holds the fabric in place, and if it's damaged the fabric may not smoothly pass through the machine. You may need to replace the presser foot.
Does your machine simply not turn on? One of these may be the root cause.
If the machine won't turn on, check to see if the foot pedal is plugged into the wall and the machine.
Press the power switch and nothing happens? You may need to replace the power switch.
Does the sewing light not turn on? This section may have your answer.
If your light bulb won't turn on, it is likely you need to replace the lightbulb.