How to repair a singer sewing machine's tension
The Singer sewing machine has come a long way since it was first produced in 1851, but even modern machines need attention from time to time. If your Singer sewing machine makes loose stitches or the thread is not moving through the fabric evenly, your sewing machine may have a tension problem.
The good news is that fixing a tension problem is easy.
Make sure the machine is threaded properly. Take the thread out of the machine and start again from scratch. Refer to the owner's manual because different machines, even if they are all made by Singer, might be threaded differently. If your machine is incorrectly threaded it cannot sew properly.
Examine the bobbin carefully and make sure it has been threaded properly. The thread should be flat and evenly spaced. If the thread is all at one side you will need to remove all of the thread and redo it.
Make sure that there is nothing lodged in the bobbin mechanism. Tiny pieces of thread can fall into the machine when you are using it. If, over time, these build up and get stuck in the bobbin, it will affect the efficiency of the machine.
Make sure the bobbin has been inserted into your Singer sewing machine correctly. If it has been put in upside down the tension will not be right.
Adjust the lever or dial on your Singer sewing machine until it is the correct tension for the fabric you are working on. A lower number loosens the tension, for when you are working on thicker fabric. A higher number will tighten the tension, which is suitable for more delicate fabrics.