I have a Husqvarna 550. The bottom thread suddenly started clumping and the machine now makes a clunking noise. This happened suddenly. I have rethreaded 3x, nothing visible in the bobbin case.

It sounds like it needs professional servicing and timing purely because of the 'clunking'. It shouldn't clunk.



https://www.google.com/search?q=Huskylock+905+Serger+thread+D+keeps+breaking

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We all know that proper threading makes for happy sewing machines and happy stitchers. And while we emphasize threading with your presser foot up- there are a few other things to keep in mind while threading your machine to make sure your sewing time is happy time!
Have you ever been sewing along on a project, decided to change threads, and all of a sudden you hear a THUNK CLUNK THUNK when you start sewing again?
If not, good for you. But I know that this has happened to a lot of our customers for sure!
Often, this sound comes from not getting your thread in the take-up lever while threading.
If you have a new needle that is the appropriate size/type and your machine is clean, but you start to hear a clunking sound after rethreading, this is the first thing to check. And it's such an easy fix. In fact, I think some people are so surprised when we tell them to simply rethread, because the sound is so terrible they think something is seriously wrong with their machine.
Now, there could be something really wrong with your machine, but the biggest clue that it's a missed take-up lever is that the problem starts suddenly, most of the time after rethreading. (machine was sewing just fine before that).
How do you make sure to thread your take-up lever?
On some machines, it's very easy to see the take up lever, and on others it's hidden behind the machine casing. Here's what you should do to try and ensure success.
-Raise your presser foot!(Full rant here)
-Put your needle in the highest position (use the needle up down button or line up the notch on your handwheel with the casing of your machine- more info here)
-Clear the thread path. Make sure there's no thread wrapped around a spool cap or trapped under your spool.
-Feel it! If your presser foot is up and your needle in the highest position, hold the thread near the spool with your right hand and thread with your left, you'll be able to feel the thread slide into the take-up lever.
-STOP immediately if you hear a THUNKing sound and re-thread. What's happening is that your top thread is not regulated, and it can ball up undereath the feed dogs and cause issues.
-Clean out your bobbin area and re-thread if you think you missed your take up lever.

Make sure the presser foot is in the up position. This will open up the tension disks. It takes a lot of patience to remove imbedded thread. Use tweezers to grab the thread. Rock the handwheel backwards and forwards to help release the thread. If all that fails, have it cleaned by an authorized Husqvarna Viking dealer. You can find your nearest dealer at the viking website - http://www.huqvarnaviking.com/us

If it were my machine I would pull the back cover for better access to the rotating shaft and remove the remaining thread. If the thread works its way into the shaft bearings you will have a real mess.

Bernina 880 - the dual feed will suddenly start making a loud "clunking" noise and making very tiny stitches. Then just as suddenly it will begin to work again - but the stitching is clumped, uneven with loops on the back. Then it will start working fine again until the next time... I called the dealer and talked directly with the repair person. He had never heard of that before. Anyone have any answers? Did I get a lemon?

There are two things that come to mind that may be causing the problem.
1) Change the needle, for it could be bent even thought it may not look it. (This is the most likely cause).
2) Have a look just inside and check if any screws have come loose. This has happened to me. (Even the repair man did not find it.

When you say "the spool side" I assume you mean the bobbin. There are a couple of reasons why this could be happening. First re-thread your upper thread with the presser foot up and check to see if the top thread is firmly in the tension disc. Usually when you have looping of thread on the underside of your fabric, it is the upper thread that is out of whack. Just the opposite of what you would think! When you're sure the top thread is right check your bobbin to make sure that's wound tight and not "mushy." When you start by wrapping the thread around the bobbin by hand and then put it on the winder to fill it, it is not tight enough so the whole bobbin winds too loose. This can cause clumps underneath. The last thing to check is that the bobbin thread is caught in the tension slot in the bobbin case and that there is no stray threads in the bobbin case opening to cause trouble. Hope this helps. Good luck. You have a great machine!

Sounds like the D needle is hitting something in the loopers and an adjustment needs to be made. The adjustments are ever so slightly. It could be that the needle bar is twisted causing the D needle to hit. It could be the looper is not within the specs for proper operation, etc. Suggest you take it to an authorized husqvarna viking dealer for service. You can locate a dealer near you by visiting the husqvarna viking website and clicking on the Dealer link on the left-hand side of the page - http://www.husqvarnaviking.com
Good luck.

The threading may be out of the channels. Rethread. Put in a fresh needle. Make sure you are using an embroidery needle and a new one for each new project. You can't use YLI bobbin thread. It stinks. If all this doesn't help, take it in to be checked These work great when there is not thread stuck in the bobbin case and it is threaded properly. If all is well, it will go like gangbusters.

frustrating huh?  it happens!  even to us that have been sewing for 50+ years, but the solution is very simple.  Top thread tension is the culprit.  pull the spool all the way off and rethread the top, follow the threading path precisely and make sure the thread goes down into the tension discs.
one more thing - when that happens often times the piece has to be removed from the machine by cutting those annoying loops on the bottom.  if this is the case, make sure you have removed all the thread clippings from in and around the bobbin case.  sometimes one little piece of thread will make you want to use swear words.
good luck and happy stitching.