I am trying to adjust the bottom tension on my singer stylist 513, but i cant figure out how to do this?

It is the flat spring that the thread goes under when you put the bobbin in the bobbin holder
however it very seldom needs adjusting as it takes just a very small movement of the screw to make a big tension adjustment
I suspect that you have bunching or birdnesting under the material and if that is the case it is the needle tension that has to be adjusted up

Generally, thread tension should be adjusted at the top thread. Only in extreme cases should the bobbin tension be adjusted.

http://www.singersewinginfo.co.uk/tension

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