Thread breaks on the 2340CV Brother. Doing two needle and the right needle is breaking at the needle. Change needle and retreaded several times

Sometimes the thread is not compatible with the material. Or wrong size or blunt needle. Or old thread. Different thread in the bobbin and top. Hope this helps:)

increase the needle thread tension

First make sure you are putting in needle correctly, it has a flat side.
Insert a new needle into your sewing machine with the flat side away from you. Push the needle into the clamp until it touches the pin (a) and stops. Firmly tighten needle clamp screw with the screw driver.
if you find all the thread bunched up then look at your thread not being routed through all the the locations. Go slow and retread from beginning.

If your bobbin was in wrong you would get the "crows nest" on the underside of the fabric. There can be several thing that can cause this: your tension is to tight, for normal sewing is usually around 3-5 (check your manual for proper setting). Your needle or throat plate can have a bur on it that is snagging the thread causing it to break. Needles should be thrown away after 50 hours of sewing to avoid problems. The needle can have a slight bend (from over use) and is rubbing on the throat plate causing it to break. and finally...your just not holding your mouth right! :) (...and sometimes this is really true!). Check your tension, pull the thread, change your needle, rub your finger over the throat plate be sure all is baby skin smooth, re thread you machine...deep breath, relax and start again. Hope this helps, Happy sewing.

Not sure where you can take it. Check your thread tension and bobbin tension. Make sure they are not too tight. Also, how old is your thread? Many times, old thread will break easily. Check your needles for burrs. If there is a burr, the thread will break constantly when the needle moves up and down as it catches on the plate.

here is a link for a free manual for the serger, it should have the information in it
http://www.brother-usa.com/VirData/Content/en-US/HAD/Consumer/UsersManual/UM_1034D_ES_178.PDF

Here you go Angie: look on page 6 of this pdf. I recommend that you print this, put it in a zip lock bag and tape it to the underside of your table.

http://www.raichert.com/adobe/MO804-12-16%20Inst.pdf

Basically Any serger is threaded like this.

Upper looper, Lower Looper and then needles from left to right. Any time you break a thread you have to start from the beginning taking the thread out and starting over.

If you want to change colors. Clip the threads near the spools, change out the color and tie the thread to the previous color... gently pull through the thread path to the needles. Clip the knot and thread the needle.

hi Patricia.
It could be the needle, the tension too tight, mis-threading, the thread weight.
try these links out and see if it helps you.
Sewing Machine Problem 1 Thread Breakage
Sewing Machine Thread Keeps Breaking
Why Does My Thread Keep Breaking While Sew
FAQs Troubleshooting LS 1217 Others Brother
Brother LS 1217 Mechanical Sewing Machine upper thread keeps on breaking...

try a tension a 3 to 5 on the top tension
try changing to a needle or if it's a new needle make sure the flat side of the needle faces the back of the machine and pushed all the way up into the needle holder
make sure the needle & thread are correct for each other, if the needle is to thin or to heavy for the fabric it will not work

I had the same problem with the blue thread- it would sew and inch then pop- mine worked wihtout breaking after I re threaded in this order: green, blue, red then yellow