Singer Model 5523 runs but doesn't make stitches. Needle is threaded and bobbin is fine. It moves but when I check the stitches there are none. Thread is not breaking.

needle /hook timing , incorrect needle thread tension or worn bobbin shaft

Try a brand new needle. Make sure the thread is suitable to the needle and fabric you are using. AVOID old or bargain bin threads. Spend an extra dollar or two for good thread.
All About Needles

Check that there are no loose threads stuck in the upper thread path, ie the tension disk.

ALWAYS RAISE the presser foot when threading the upper thread. Verify that the thread path is correct. Mis-threading will invariably cause broken thread.

Clean out the bobbin area & feed dogs of any lint and loose threads. Check that the bobbin has been installed & threaded correctly and turning the right direction in the bobbin case.

Manually rotate the handwheel one turn until the upper thread grabs the the bobbin thread. Pull it the rest of the way to the top. When beginning to stitch, start slowly and gently hold both thread tails in your left hand until it has made a couple of stitches.

How and Why to Bring up the Bobbin Thread

If you have a manual, make sure you follow the maintenance tips. If the machine needs oiling, be sure to follow the instructions using only fresh good quality sewing machine oil. Most machines that have been given as gifts from a sewist's stash may not have been maintained regularly.

If it still does not stitch properly, take it for service. It could have a timing issue, ie the needle arrives at the bobbin at the wrong time to intercept the bobbin thread.

Singer melodie 40 user manual

Turn your machine off and leave it off. Remove all bobbins - in the machine & from the pin. Remove all thread - from threaded machine and bobbin thread path. Clip the machine thread at the spool and pull the needle thread towards yourself. Clip bobbin thread at spool and close to bobbin, then pull towards you through thread guides. This keeps the tension where it belongs. Move the bobbin winding shaft from normal sewing back to winding bobbin a couple times. It should click in place when moved to the winding position. Check to see if there is any thread that has slipped under the bottom of the bobbin and wound itself around & under the bottom of the shaft. Carefully unwind to clear. If the shaft does not easily move back to the sewing position it is probably stuck in the winding position. Don't force it, but try to get it out of the winding position. Leave it to the left in the normal sewing position (unclicked). Check to see if there is any thread caught anywhere along the path from spool to the winding pin. Pay close attention to the first thread guide and the two discs the thread slips between that control tension. Hand wind the wheel on the right towards you to raise and lower the needle a couple of times. Stop with needle in highest position. Do NOT wind hand wheel backwards (away from you). Make sure the bobbin pin is not in the winding position. Now turn on your machine. Needle should jump to default position. Move the stitch length and stitch width guides to the far right, then far left, to attain the green lights. Press the reverse stitch button to raise lower and raise the needle. It will stop in the highest position. If you still have the error code - make sure the bobbin winding pin is NOT in the winding position. Remove the needle. Lower the presser foot and run the machine without any thread a bit. If the needle bar does not go up and down most likely the bobbin pin is stuck in the winding position. If the code has cleared use your manual to carefully wind a new bobbin. Make sure you are using a 15J bobbin which this machine requires. It will not work with just any bobbin. Next, raise the presser foot then carefully thread the machine. If you don't have a manual you can download one from the Singer website. You might consider cleaning the entire machine paying special attention to the hook area and feed dogs while the power is off. If you find a lot of lint do this more frequently to prevent buildup. Take special care when replacing the bobbin care. Hope this helps. If not call Singer. It may take some time but you should be able to reach someone to help you troubleshoot. If this is an older machine I recommend taking it for repair yourself instead of sending to Singer

reference: http://www.amazon.com/Singer-7466-Electronic-Sewing-Machine/forum/Fx3BSOY0VA78VQ4/-/1?_encoding=UTF8&asin=B000B91B3K

it's possible that the machine may need a adjustment, or could have a broken part.

check the torque on the lower bobbin down needle needs to be able to pick up the lower thread.

try rethreading the machine top & bobbin
change the needle--flat side to the back of the machine, make sure the needle is the right one for the fabric being sewed
clean under the needle plate & in the bobbin area for lint or theads

try adjusting the top tension & see if that helps

Mine is doing the same thing. It's pulling the thread up from the bobbin and making a huge knot. Any suggestions. I've done all the above checks. Brand new needle, tension is on embroidery, threaded properly and no lint in bobbin compartment.

First easy thing to check, are you using the correct length needle.
If this is not the problem then somehow the needle bar has moved and the the needle depth is to high or the timing is wrong..
Unless you really know what you are doing then I am afraid a sewing machine tech needs to reset the needle depth and subsequently the timing.

Try moving the stitch length dial to 4 or 5 - check the manual. You may have it in the position for very close together sewing. I had to do a lot of trying with my 4795 to get it to work right. I found that very thin thread, polyester kind, broke at the needle after a couple of stitches. I switched to coats & clarks thread and a Singer ball point needle and it works fine. Be sure your needle is inserted with the flat top toward the back of the machine. Good luck!