How to fix loose metal screws

Remove all the thread from your machine. Install a brand new needle. Raise the presser foot and re-thread the upper thread, making sure you are following the correct threading sequence. Confirm that the bobbin thread is threaded through the bobbincase properly. Now, perform another test stitch. Is the bobbin thread still looping?

If you have already tightened the upper thread tension and the bobbin tension is still too loose, then you may need to tighten the bobbin tension. First, mark with a permanent marker where the slash of the screw head meets the bobbin case. This will mark where the screw was originally set before you begin making adjustments and allows you to return the screw to that position should you need to.

Set the upper tension to the halfway point between the high & low number. This is what would normally be the standard.

Then gently turn the bobbin tension screw to the right 1/8th of a turn at a time. Then test. Keep adjusting until the bobbin thread tension is correct. The tensions are correct when the upper thread and the bobbin thread meet in the middle of the fabric.

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sometimes it is the blade and not the clipper

if you look under the sink at the bottom of the tap there should be a long threaded screw with a nut fastening it to the sink by a curved metal bracket and a rubber washer,( try tightening this.)sometimes the bracket and washer corode if they have then you will have to replace them

It is usually a little tiny screw on what holds the bobbin in and where the thread passes through the bobbin. (The holder...not the metal or plastic bobbin spool of thread...it's sometimes called a shuttle to avoid confussion.) When you tighten or loosen the screw on the bobbin holder it puts more or less pressure on that metal hook the bobbin thread passes through.

In most cases, this is caused by loose threads and fluff being in the upper tension unit rather than a problem with the bobbin. There is a screw on the bobbin case that losens and tightens the resistence. However, it can easily come out and then you have a mess.

Try this to check the bobbin thread tension -
Take the bobbin case holder out of the machine. Use a bobbin that is about half full and use standard 50 wt sewing thread.
Take your needle plate (the metal plate over the feed dogs that has markings showing stitch width under the presser foot).
Thread the bobbin thread in the bobbin case, holding the case so that the thread is through the tension spring as though it is in the machine, tied the end of the tread to the needle plate and have it hang below the the bobbin case.
If the needle plate immediately drops to the floor, unwinding the bobbin, the bobbin tension is too loose. If you jiggle the bobbin case slightly up and down and the needle plate moves slightly down, it is just right. If it does not move at all it is too tight. The resistence should be 14g which is the weight of the needle plate.

The upper tension unit, look straight down from the tension unit and you should see some metal disks which the upper thread rides through when threaded. Take your small cleaning brush and brush out any loose threads/fluff there. Look down the left side of the tension unit to make sure there is none hiding.

When you tighten the upper tension unit by pushing the tension buttons on the screen, do you hear the tension disks tightening? If not, it may be the pc board or the tension unit itself that will have to be replaced.

Otherwise, you might want to 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