Consew is not as well-known as other brands of sewing machines, but the company manufactures sewing machines and quilting machines. There are many advantages to these machines as they feature a safety clutch, the ability to sew well on lightweight and heavy materials and it is possible to change the bobbin without removing it from the machine. Most of the problems that occur with the machine are due to improper threading, not enough lubrication to moving parts or improper thread tension.
Check that the machine has sufficient oil at the necessary spots. The machine has many points that need oiling. If there is not enough lubrication at any point, then many problems can occur such as timing issues, thread frequently breaking and even discoloration to the fabric. Use your owner's manual to ensure all necessary points are properly oiled.
Check the length of your stitches. Uneven stitches are due to improper timing, bad tension or an improperly wound bobbin. Make sure that the bobbin has been wound evenly. The tension bracket on the bobbin should be adjusted to achieve an evenly wound bobbin. Check the tension of the upper thread and that it has been threaded through all necessary points.
Ensure that the tension on the upper and lower threads are equal to each other. This will produce perfect stitches. Turn the serrated nut on the tension device to adjust the tension on the upper thread and the large screw near the outside of the bobbin case for the lower thread tension. Turning to the right will increase the tension, while turning to the left will decrease the thread tension.
Adjust the pressure of the fabric speed if the material bunches up. Use a screwdriver and turn the screw found on the back of the machine. The screw is small and located directly in the middle of the arm, use a diagram of your machine from the user's manual if you have difficulty locating the screw. The location can vary slightly depending on the model.
Inspect the machine for bent or damaged parts. Damaged parts will need to be replaced as they can affect the timing, tension and even cause the thread to frequently break.