My singer simple keeps jamming. I know the thread is caught underneath, near the bobbin but I can't turn the hand wheel either way.

Your bobbin may be in backwards. Is it possible to put it in either way?

If you mean the Singer Style Mate 347, open the face plate and remove the old bobbin. Then, the first step is to hold the hand wheel and loosen the stop-motion screw inside the hand wheel. (Keep the hand wheel from turning with one hand and turn the stop-motion screw towards the front of the machine.) Place your empty bobbin (hole away from the machine) on the spindle near the bobbin winder switch. Feed the thread from the spool on the spool pin through the eyelet on the top of the machine (near the top thread take up) and then down to and around the bobbin tension disc below the on-off power switch. Pass the thread through from the inside of the bobbin to the outside of the bobbin. Move the bobbin winder switch to On and hold onto the end of the thread. Start the machine and let a few winds get placed on the bobbin then stop for a minute. Cut the thread near the bobbin. Restart and continue winding more thread onto the bobbin until you have enough thread or the bobbin is full (it will stop automatically). Move the bobbin winder switch to off and tighten the stop-motion screw.

For pictures, see pages 6-7 in the manual. It's available as a PDF here: http://www.singerco.com/uploads/download/9b8c1ca7584c2bea7837ca4bf5338af7f1b5380e.pdf . (These are pages 8-9 of the PDF.)

I hope this helps.
Cindy Wells

Have you tried re-threading it? Remember to keep the presser foot up as you thread so that the tension discs are open. Re-thread the upper thread because it can often cause bobbin jams.
Perhaps your tension discs are blocked, try running a thicker thread through by hand to clean them.
Check there are no broken threads in the bobbin raceway.
Sometimes the wrong size needle upsets the tension.

The needle either not moving or stopping is a sign that the machine is jamming. Here's the answer for the question "My machine is jammed" from the FAQs on Singer's web site at http://www.singerco.com/support/faqs.html

A jammed machine is caused by thread being caught in the hook. Remove the upper thread and the bobbin case, turn the hand wheel towards you (counterclockwise) by hand and remove any thread in the bobbin case area. *Always turn the hand wheel towards you. Turning the hand wheel away from you (clockwise) can cause the machines timing to become unaligned and jam your machine. Also, always make sure the presser foot is in the down position before you start sewing. Sewing with the presser foot in the up position will jam your machine in the bobbin case.

Your description of the needle hitting the plate or foot is an indication that the machine's timing has become unaligned which can be caused as indicated above by turning the hand wheel away from you - the correct way is to *Always turn the hand wheel towards you.

A jammed machine is caused by thread being caught in the hook. Remove the upper thread and the bobbin case, turn the hand wheel towards you (counterclockwise) by hand and remove any thread in the bobbin case area. *Always turn the hand wheel towards you. Turning the hand wheel away from you (clockwise) can cause the machines timing to become unaligned and jam your machine. Also, always make sure the presser foot is in the down position before you start sewing. Sewing with the presser foot in the up position will jam your machine in the bobbin case.

Are you sure that there is no thread caught in the bobbin shuttle? Threaded right? Plug completely inserted? If yes, call Singer at 1-800-4singer

I would say that the threading is wrong somewhere, watch your dvd and read the owners manual, also go to Singer.com FAQ for your machine, If the jamming is underneath, it is the top threading problem, on top, it is the bobbin thread either has lint or stray thread or thread not coming out the right direction for your bobbin, I am sure that it is just a simple solution, I also use metal SA 156 bobbins and have no problems,

You need to remove the bobbin from the "race" by following the instructions in the manual. Give it a good clean and remove any bits of fluff and thread. Remove the upper thread also andmake sure that the tension wheel is clear of any broken threads and is on the correct setting. It may have been threaded wrong. The hand wheel not turning sounds like the bobbin area is jammed also.

The zigzag setting should not have caused it to jam up unless the tensions were off and the thread was bunching up on the bottomside of the needle plate. If you ever jam or break a needle be sure to replace it with a fresh new needle. A slightly bent needle will cause all kinds of problems.
When putting the bobbin back in make sure you keep a good amount of thread hanging out and manually turn the hand wheel around until the needle make a full rotation. The hook should catch the needle thread and allow you to pull the bobbin thread out through the needle plate.
If you jammed it really good it is possible that the needle and hook timing is out of sync in which case you may need to have it re-timed.

Needle jams....Thread is caught in the hook...solution...Remove the upper thread and bobbin case,turn the handwheel backwards and forwards by hand and remove the thread remands.

Needles breaks
1. Needles is damaged..Insert new needle
2. The needle is not correctly inserted....insert flat side towards the back
3. Wrong needle size for the fabric...Choose a needle to suit the thread and fabric.