Stitching Problem

[Windseeker]

I ended-up getting a Pfaff 130 off Ebay. It should be just fine for the fun projects I have in mind. I have some practice acryllic canvas I'm using to test the machine out. After hours of practice, I finally have it adjusted to interlock the treads. The only problem is it makes a bad stitch on the bottom. I looked in the manual and it says bad stitches can be caused by the tensions not being equal. The lower tension on the bottom bobbin is fairly light, but the upper tension is tight. I mean, you have to wrap the tread around your hand twice, brace your foot against the back of the machine then pull with all you got! Not really, of course, but I wouldn't be surprised if it was 10X the bottom tension just from feel. Since it is interlocking in the middle, my tensions should be correct, then why do they feel so different? Why is the bottom stitch not right?

[Windseeker]

I figured it out. Not enough tension on the bobbin spring. I decreased the upper tension slightly, then gradually increased bobbin tension 1/4 turn at a time on the screw until the stitches were tight on the bottom. Then increase the upper tension until the interlock is in the middle and Viola! Perfect!