Blind stitch hemming

I have a White sewing machine model # 4075 ( Jeans Machine ) When I try to sew a blind stitch the lenght of the right side stitch is is between 3/16 and 1/4 inch. The hidden stitch pulls the fabric together and creats a seamlike line that can be seen on the right side of the fabric. I follow the setting according to the instructual manual, zigzag at 5, stitch length at 2 and pattern selection dial at 6. Can anyone tell me what I am doing wrong or what else I should be doing to solve this problem?

                                                      Thanks

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