I'm having a serious problem with balancing the thread tension.
From the top: stitch appears balanced
Bottom: thread is straight and the knots are clearly visible
According to the thru-hiker page, the "bottom thread too tight, tighten top tension".
I have adjusted the sewing machine according to the manual's specifications. And tried all of the suggested adjustments I could find online. The bobbin tension is perfect – when it is removed from the machine and swung by the thread, only about an inch of thread is released then it stops. I have adjusted the bobbin to both ends of the tension spectrum and STILL have the same problem.
I have adjusted the top thread tension to the tightest or loosest settings and STILL have the same problem. All combinations of top and bottom tensions still have the same problem shown in the images below.
TOP

BOTTOM

The machine is a Riccar 906E. It is a basic but quality machine. Not brand new but still well cared for. I am using a 70/10 needle. The package says "Schmetz Universal 130/705 H 15x1H 70/10". I have tried many other types of needles with the same result. I am using a synthetic thread purchased from the sewing shop. I have also used gutermann thread with the same problem. Same problem with other fabrics.
Does anyone have any suggestions? It really sucks having the stitch like this on everything I sew, and i'm reluctant to start large or expensive projects with the machine in its present state.
Maybe someone can refer me to an active sewing community that might better address this? I couldn't think of anywhere else to seek help – i'm really desperate!

