BROTHER LS-1217 THE BOBBIN TENSION

not sure if this link will help you but have a look.
brother LS 1217 Tension control knob locked in position Google Search

Are you sure that it's a Singer LS-1217? I can't find any model with 1217 on the Singer site.

The Brother LS-1217 manual is available here: http://welcome.solutions.brother.com/bsc/public/eu/eu_ot/en/doc/manual_top.html?reg=eu&c=eu_ot&lang=en&prod=hf_ls1217euk . The direct link to the English version of the manual is http://download.brother.com/welcome/doch000000/ls12171217b13171417ug01enesfrpt.pdf . There are only a few knobs on most machines. On the front near the needle is the Needle Thread Tension knob. If you use contrasting colors (different top, bobbin and fabric colors), you might see a straight stitch where the top thread is visible on the bottom of the fabric for example. Adjust the tension to get both the top and bobbin threads meeting in the middle of the fabric layers. (Increase the needle thread tension - rotate to a higher number but go in 0.5 increments.)

Then you have near the motor area the stitch width and length knobs. The width is only for zigzag stitches. A long stitch length is good for a temporary seam (like basting in a zipper or hem) before you finish that area. However, the width and length should be adjusted depending on the fabric. A fine fabric needs a smaller stitch, usually. The knob on the right side of the machine is the balance wheel (or hand wheel). This adjusts the needle height so that you can have the needle out of the way while changing the bobbin, for example.

I hope this helps.

Cindy Wells
(I use the Singer Sewing Book as a reference for tension issues.)

remove the thread and bobbin.
take out your manual and follow the exact instructions for threading and inserting bobbin.

If this does not help check the tension on the top(the number should be about mid way).
If it is too low it will bunch up on the bottom.

The problem is most likely thread tension. First try loosening the upper thread tension (numbered wheel on left side of most machines), if this doesn't rectify the problem then check the bobbin case tension. Correct bobbin case tension can be verified by holding the bobbin case with bobbin inserted and thread extended several inches. If you grasp the thread the bobbin case should not descend rapidly (fall) but should unspool slightly when thread is quickly tugged upward. Please refer to attached picture or your owner's manual.

You should be able to fix this. IF it is the top thread on your fabric that is screwy you need to adjust the bobbin tension.
If it is the bottom thread you have a problem with your upper tension. Blow out the upper tension assembly using canned air, the tension discs may be dirty

Make sure you have enough of a "tail" from teh bobbin... Probably 4 inches or so before starting. If that doesn't work, check upper tension and needle is properly seated.

The needle drags the thread down and then starts back up causing a loop at the eye which a shuttle goes through and acrries the upper thread over the bobbin. The upper thread then drags the bobbing thread up.

A mass of loose thread on the bottom of the fabric most likely indicates a total loss of upper tension. Remove the upper thread, raise the presser foot and rethread the machine. Make sure that the upper tension knob/dial is around 5. If you still have a problem, let me know what brand and model you have.

needle won't pick up bottom thread. I have a brother LS 1217

have you tried other thread and a different bobbin?  The tension screw on the bobin case could be too tight.

just wind the thread around the bobbin, don't put it through any holes, wind it around the center pole,