My machine was sewing fine and suddenly decides to... (by 8 users)

The very first thing to do is put in a new needle. A dull needle will cause this for sure.
After that it may take a tech to make some adjustments.

1) The hook is slightly out of time. On this type mechanism, there is
a slight difference in timing for the different needle positions.

2) The needle bar is slightly too high.

3) The hook and needle are too far apart, and then the skipping would
be more apt to show up on light weight fabrics.

could have jumped time also

Change the needle and make sure you have the right needle for the fabric. Yes, it matters!

Try rethreading, making sure to hold tension on the thread while threading the take up lever---pull the thread end up towards the ceiling then back down.  Sometimes the thread will escape the take up lever if it is not in all the way.

Many thanks to Mini Me! I had worked and worked on the tension, to no avail! I was ready to toss the machine when I came across your solution! Changing the needle should have been the first thing I thought to do...but without your help I might never have! It sews perfectly, now....thanks a million!

Hope you found a solution but I just want to say that emnsam is a genius!  Their suggested solution solved my problem that I had where the top stitches were loose.  No more 2-for-1 threads from the special bins.

Check the thread you are using. A good name brand thread will give better results than the bargain bin threads.

When you look at bargain threads there is a lot of fluff and stuff coming off of the thread which can cause the thread to come off the spool unevenly and skip.

i suggest that you return your sewing machine to ehere ever you bought it from and tell them that it's skipping stiches. if they won't take it back then get a new one

if there is alot of thread bunching up under neath your work, then the cause of this is no tension on your top thread.-either incorrectly threaded(very easlily done)through the tension discs or -there is some fluff or thread or something caught in beteen tension discs.i know it sounds strange that it is the top thread causing problems undernath, but trust me it is.this is why the bobbin jams aswell,because there is no tension on the top thread,the take up leaver( the thing that goes up and down when you sew)cant pull the thread around the bobbin case, so it jams up. hope this helps