My tension housing wont change when i turn the dial and the thread cannot be pulled through it, it gets stuck

Guessing it is the top tension? Turn the tension dial to a smaller number. There could also be debris/gunk in the tension disks. If you dip a piece of cotton thread (like perl cotton) into rubbing alcohol, squeeze out the excess, loosen the tension dial all the way, RAISE the presser foot, then gently pull the cotton thread DOWN between the tension disks a few times (like you are threading it). That should clean out any gunk stuck in there.

indications of a bobbin tension incorrect is the bottom thread lies flat under the bottom material
it seldom needs adjusting but if you have to the spring plate that you pull the thread under as you put the bobbin back in the holder is where you adjust it
there is a small screw that holds that plate on so the slightest movement of the screw makes a lot of difference of the thread tension
all thread tension problems relate to the needle thread tension and if you have it set to 0 then the thread will be bunching up under the material
you don't say what the issues are but pounds to peanuts , it will be the top tension that is the problem
It will be correct when you are threading the needle , you pull the thread out first before threading and there is a resistance to pulling the thread

First, dial the tension all the way down and see if it changes. Next, check to see if the disks lose tension when the presser foot is raised, they should. If they don't, they may be stuck and not moving. You may be able to prod them gently with a screw driver and move them back and forth to get them to release.

If you are only getting good tension when the top tension is set to zero, then you need to adjust the bobbin tension. The two threads are at tug-of-war with each other. The correct tension is when both apply the same pull against the other so the threads meet in the middle of the fabric. In your case, the bobbin is not applying enough tension on the top thread.

Understanding Thread Tension Threads

You might try cleaning the top tension with a piece of heavy cotton thread and alcohol. (Wet a length of cotton thread in alcohol, squeeze out any excess, and then slowly pull the thread "down" between the tension disks like you are threading. Do this several times.) There could be gunk stuck in there.
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When you say one tensioner is broke what makes you think that?
Try to pull the thread through the discs and see if turning the knob changes the tension. If it is leaving loops this may or may not be a tension problem. As a test you can pinch the thread and see if that corrects the loops with increased tension. Otherwise you need a service tech.

Possible causes:
top tension dial set too low
top tension dial not working at all
top thread not seated into top tension discs
top thread hasn't been threaded up correctly, missing out the tension discs or take up lever

Most likely your top tension device is either set too low, or gunked up and not working right or has actually failed. Can you access the tension discs? If so, turn dial to zero and 'floss' between the discs with the selvage edge of a clean piece of waste cotton fabric and see if any black stuff comes out. If so, continue until it comes out clean. Turn back to 5 or the marked normal setting.

Now thread up again from top spool down to tension, through take up lever, then down to the eyelet just above the needle. Lower the pressure foot to engage tension then pull on the thread downwards. Is it hard to pull? If not, then the tension dial is faulty and you'll need to get the machine serviced.

If this feels firm and hard to pull, then take a look at the lower thread tension but this shouldn't normally need any altering (unless you've adjusted it previously for some reason and not reset it to normal setting). Check thread is fully into the tension spring, bobbin is in the right way and bobbin case is in fully in the correct position.

If you look at the zig zag stitiching you've done, can you identify if the loose thread is the top one? If you use two different coloured threads for troubleshooting, this often makes it a bit easier to see what's happening, just make sure they are the same weight and brand of thread if you do this.

I hope this helps you to identify the problem and fix it. But if you suspect that the top thread tension device is just not tensioning the thread even if you turn the dial right up to 7, then you'll need to get the machine serviced as the dial could well be faulting.

Have you changed the needles in your serger before this happened?

If so, check again that the left needle is fully up into its housing and that the needle is in the right way with the scarf (cut out) at the back. Have you got a ball point needle in one side and not the other perhaps. If you are seaming knits, then put in 2 ball point needles, if for wovens, then two sharp needles.

Now check tension on left needle, is the number on the dial the same as the right needle. Pull on the left thread just after the tension disc then the same on the right thread, does the tension feel the same on both?

Is the thread catching somwhere on the aerial, caught on the cone holder, or at the back somewhere or as it comes through the tension discs? Take thread out of the discs, turn dial to zero and give between the discs a good clean with the selvage edge of a clean piece of cotton waste fabric, saw it back and forwards to clean out the discs. Now thread the machine again again. I'm assuming this is a 4 thread serger, so thread order would be top looper, bottom looper, then right needle, left needle, turn tension to zero on all threads, pull all four threads out under the foot, loower the pressure foot, turn tension back to five on all (or whatever your normal setting is) then chain off a little and test sew.

I hope this helps resolve your issue.

If the bobbin thread is coming up to the top, then the thread is not under tension correctly. I think that this is a top loading bobbin so the bobbin will go into the bobbin holder, then you pull the thread back and press it into a tension device - should hear it click into tension. Now pull the thread back towards you and it should not come out of the tension. The bobbin should turn anticlockwise as the thread is pulled from it.

These bobbin holders usually will have a small adjustment dial on them and it should have the standard setting marked in red. It is very unusual that you would need to change this but check that it hasn't been messed with perhaps. If you have the machine manual check where they say the dial should be set. More likely that the thread is just not into tension fully or at all.

The manual may give you other troubleshooting tips too.

A good resouce is www.sewing.about.com for general machine tips, cleaning and threading issues.

Hope this helps.

The problem is never the bobbin when you have this problem. It's the top thread. Take the thread off the top of the machine and rethread the top. Make sure the small tension dial is on 4 or 5 (the larger dial on the front left is for the pressure on the foot, not the thread tension.) After you thread the machine, put the pressure foot down but NOT on the thread. Then pull gently toward the back of the machine. When you do, the needle should bend slightly backwards before the thread comes through the machine. If it pulls with no resistance you could simply have "fluff" or remants of thread between your tension discs. If you do, put the dial on zero and using an old needle, clean between the discs and try threading the machine again with the "pull test" I described earlier.
No tension on the top of the machine, lets the bobbin tension win and it pulls all the thread to the bottom of the fabric.

You need to do a tension assembly test.
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(To do this test, adjust your tension setting to normal or medium or 5 or something in the middle. Raise the presser foot and pull the thread through the tension. It should pull easily!! Lower the presser foot and pull the thread. It should pull noticeably harder.)
If it doesn’t work this way then you probably have a piece of thread or lint stuck inside the tension discs. To remove it, turn the tension to 0 zero and raise the presser foot.Using a small screwdriver, open the space between the discs and spray with canned or compressed air. The stuff should come out. Do the tension test again to make sure you got everything and then try sewing again.
sewman7