Fourth thread keeps breaking, cannot find instructions to make sure I am threading correctly. Isn't there a video on the interneet available

Can be a variety of reasons. Firstly, is it a Quality thread? Cheap thread can be inconsistent in strength and also creates more 'dust'. Secondly, check the thread path for the top thread and also the bobbin thread. Reset tensions. Third, have you broken a needle lately - may have created a small burr on the bobbin / shuttle. Fourth, change the needle - is it the correct type and size for what you are sewing?
Hope that helps!

Difficult to say without really seeing what's happening and which thread is breaking. If the top thread is breaking, check to make sure the thread is not wrapped around the spool pin or a thread guide.

Just some things to try:
Install a brand new needle.
Be sure to clean and remove all the thread pieces, lint, etc from under the needle plate, around the shuttle, etc. Oil as instructed in the owner's manual.
Remove all the thread from the machine. ALWAYS RAISE the presser foot when threading the top and rethread the machine from the beginning. Check that the thread path is correct and the bobbin is loaded and threaded correctly.

Be sure to use good quality thread--no Old or bargain bin threads!
Solve Most Sewing Machine Problems With These Simple Tips

Why Does My Sewing Machine Keep Jamming Sewing Made Simple

try a new needles
check for burrs
make sure the thread is not caught anywhere

Install a brand new needle. Make sure you are using thread and needle that are compatible with the fabric you are sewing.

Change the type of thread you are using. Old or bargain bin threads will frequently cause problems.

Clean the tension disks to make sure there is nothing stuck that is preventing the thread from feeding.

Remove all the thread and re-thread from the beginning. FIRST raise the presser foot so the tension disks will allow the thread to seat properly. (Consult your owner's manual.) Make sure you are threading everything in the proper sequence and not missing any steps.

Set the upper tension at the halfway point between the high and low number.

Stitch a test on a piece of your scrap fabric from your project.

The ideal tension is when the upper thread and bobbin thread meet in the middle of the fabric. If the bobbin thread is appearing at the top of the fabric, your upper tension is too tight and needs to be loosened. If the upper thread is appearing under the fabric or forming a loopy mess, the upper thread is too loose.

Keep adjusting and testing until the tension appears correct.

If the thread continues to break, then there may be a burr that is catching the thread and breaking it. Or the timing could be off. Take it for service.

http://www.schmetzneedles.com/all-about-needles/

http://www.sewingandcraftcorner.com/why-does-my-thread-keep-breaking-while-i-sew/

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I would return the Unit to the Seller who usually has People that can Visually show you what you may have done wrong. Or go to Joannes or any Fabric shop (Not Walmart) and I'm sure there is some Lady (usually) who would be so joyous to help you!!! Really the fabric world isn;t to exciting!

If you need further help, reach me via phone at https://www.6ya.com/expert/steven_b77d19396bfe2249

Go back to your instruction manual, some available online. to Re-thread the machine completely and make sure you are threading correctly. If that's not it, you may have thread jammed in a mechanism and it needs a technician's tools to get at it properly.

Cheers,
Kelly
Embroidery Services
San Diego, CA

try changing the needle
also try adjusting the thread tension
make sure the threading is correct for that fourth thread and needle

If you've threaded the bobbin per instructions... then make sure your needle isn't damaged, bent, or dull. Also make sure the needle is seated fully and correctly oriented into the needle bar.

When threading the fourth thread (Green) make sure that the needle threads (1, 2 - Orange and Blue) are not over the fourth threader. This would cause them to tangle up with the fourth thread. This is caused when manually advancing the machine to thread the fourth thread. I run a piece of cardboard through the feed mechanism to free all threads before using the overlocker.

I was having the same problem. I was trying to thread only that 4th one because it keep breaking. It did not stp til I rethreaded all the threads and did it worked fine