Thread is knotting up under the feed dog plate getting error LO.I tried removing the plateand cleaning and replaced bobbinholder and it is still jamming. is there supposed to be any play in the bobin holder/case. it moves. thanks

Incorrect tension for material. Old knotted thread. Bobbin thread and needle thread must match. Thread and needle size suitable for the material being sewn.
Feed dogs underneath need cleaning. Thread tangled underneath feed plate. Needle too old or bent, or blunt.. Hope this helps

Or perhaps thread is knotted up in the feed dogs, under the needle plate and bobbin area. Raise and remove the presser foot, loosen and try to remove the needle, then try to remove or release the needle plate to expose the feed dogs so you can begin to clean out any thread tangles. Then open the race ring cover and remove the race ring, the entire bobbin case and hook from the machine. (If the bobbin and bobbin case are bound with thread, you may be able to remove the bobbin case and hook all as one unit.) If you can get those items removed, you can try to cut away whatever obstruction exists.

30 Removing Tangled Thread from the Hook Race FREE

Have you taken out the sewing plate and removed the feed dogs? Sometimes a huge knot of thread can get under there which disables the machine.
Best wishes

1. To solve your knotting problem. Learn to always trap or grasp your thread ends for the first few stitches.

2. When the dogs are down, sometimes you have to grasp and jiggle or turn the hand wheel while re-engaging the feed dogs.

3. It sounds to me as if you aren't making sure that the take up leaver is in the top position before you press the "foot button down" Make sure you press "needle up" before you press foot down. That way the dogs should be in the correct position for you to get the fabric under there and proceed. In the mean time... I would strongly recommend you go back to your dealer and take some lessons. It sounds to me that when you learned to sew... you were not trained the proper procedures.

Hello Emma,

Hope this helps.
When the feed dogs are lowered they will not go up with just the switch. Try this, move the feed dog switch to the up position, then turn the handwheel 1 complete rotation. Voila they should be up. Let me know if it is solved. Chris

Thread knots because the material is not feeding. Sounds like the machine has not been oil or serviced in some time and the old oil is turned into a varnish and causing the mechanisms to stick and therefore, not operating freely. I've recently serviced a machine that had been idle for quite some time and the feed dogs and zigzag mechanisms were sticking. Just a proper dissolving and cleaning the old oil and re-oiling and the machine was working like new again. A proper cleaning of lint build-up on the feed dogs under the needle plate is also a probable cause.
<Ray>

Some sergers have a threading guide inside the door on the front of the machine.

If you need a manual, please provide the brand & model.

No but I will be taking it to a Janome authorized repair shop and pay them thanks anyway. G

When the sewing machine is properly timed, all the parts work together in a seamless flow of coordination. The needle moves from it highest point down toward the needle plate. The feed dogs reach the farthest point toward the back of the sewing machine. The feed dogs drop under the needle plate. This is just before the needle point reaches the needle plate. The needle continues to move down dragging the upper thread under the needle plate. It proceeds toward its lowest point.
The needle begins its rise back up. A loop of thread forms along the back of the needle. A special cut out on the back of the needle to accommodate this loop is called the scarf. The sewing machine hook slides behind the needle. The point of the hook slides into the thread loop and pulls the thread around the bobbin. The bobbin thread and upper thread wrap together. The needle and hook proceed through their actions under the needle plate. The feed dogs move under the needle plate from back to front.

The needle proceeds to rise again up out of the bobbin area exiting the needle plate. At the same time the feed dogs rise up out from under the needle plate. They begin to move from front to back as the needle continues to rise.
The thread from the bobbin flows through a bobbin tensioner providing resistance to the thread as it is drawn up by the upper thread knot. The upper thread is also under tension. This comes from the upper tension, thread guides, tension spring, and sewing machine take up lever.
The thread from top and bobbin grow increasingly tighter until they form a locked stitch in the middle of the fabric. This process is repeated for every stitch.
How do you adjust sewing machine timing?

The needle, hook, and feed dogs must move in harmony. If they fail to do so, the machine will not perform as expected. When the hook is just slightly out of time with the needle, you will notice skipped stitches. This may begin on only one side of the zig zag stitch or intermittently. If the timing is just a bit more out of sync, stitch formation will become impossible.
If the feed dog timing is out of sync, the fabric will not move through the machine as expected. Threads may bunch up or the fabric may just not move.
As you can see, timing is everything.
click on this link directly
http://www.fixsewingmachines.com/How-to-Adjust-Sewing-Machine-Timing.html

This will help. Thanks please keepupdated.please do rate the solution positively .thank you for using fixya

take out the thread and bobbin. run the machine with the pressure foot up and watch the feed dogs (toothy things under the pressure foot that move the material through the machine). if they are not rising up above the plate, then you are sewing multiple stitches in one place and that's what spools up the threads. take the plate over the feed dogs off (it just pops up). get someone to remove the two screws holding the feed dog on (it's a torx #10). the piece the feed dogs was screwed to rides up and down on a short piece of polished rod under it. the rod has gummed up to its bearing. bright light, look for this and get some oil (3in1) on the rod above the bearing and force the feed dog mount up and down until it frees up.