Lucy, I can not help you with your machine , perhaps others can. Kay

I have this sometimes when the bobbin is almost empty or if the top thread is caught on something behind the machine.

This what I try when this happens.

First completely unthread your machine including removing the bobbin. Rethread and test.

Clean out the bobbin and feed teeth area. You will need to remove the plate to do this properly.
Place 1 drop of oil on the wick under there while you have it all open. Rethread and test.

Make sure the foot is up then loosen top tension slightly then rethread. Check stitching. Repeat if needed.

Insert a new needle or one you know for certain is ok.

If it is still not working try a different thread and bobbin combination.

If that still does not work you can tighten the tiny screw on the bobbin case. I only do this as a last resort after I have tried everything else. Usually it is one of the above things.

If all of the above fail the tension spring may need to be replaced so a visit to the dealer for repair may be necessary.
Let us know how you go

LUCY, I CANNOT HELP WITH YOUR MACHINE BUT YOU HAVE BEEN GIVEN GREAT ADVICE FROM Sewmum1

Yes, to what has already been said. When you rethread the top, rethread the bottom and vice versa, or as my teacher put it TOP TENSION IS BOTTOM TENSION. BOTTOM TENSION IS TOP TENSION.

if you haven't changed your brand of thread and this has just started chances are you have a bit if thread caught in the top tension area-also you can get a build up of gunk off the thread if you have used it a lot- get a thin piece of cloth with some metho on it and drag it though the top tension area -gently. Also get as bright a light as you can to shine into the area because it is easy to miss thread scraps with normal light. If you have changed your brand of thread it may just be a case of reducing the top tension- ie from say 2 to 1.5- good luck

I had this problem with my V5, and ended up getting a new bobbing case ,
Hugs pam

LUCY, I USE DENTAL FLOSS TO CHECK FOR ANY THREAD CAUGHT IN THE TENSION GUIDE