Too much lower thread at the wrong side of the fabric

Our advises : If increasing the upper thread tension the stitch is correct at the wrong side of fabric, the problem is solved. If adjusting the upper thread at the maximum you still have the problem, then you have to increase the lower thread tension of the bobbin case. Otherwise your upper thread threading could be uncorrect. In any case please look at the following explanation :

*Upper thread tension adjustment
*Lower thread adjustment at the bobbin case
*Upper thread threading