Sewing Machine Problem

I have Kenmore machine (not sure of the model, but a pretty basic machine) that is only a few years old and I've only used it a few times for mending.  I was trying to fix some used cloth diapers and my machine keeps messing up.  For a while it kept nesting and skipping stitches.  Now the needle moves but it doesn't sew.  When I pull it out of the machine there are no stitches in the fabric, just holes.  I've threaded and re-threaded it, cleaned the bobbin holder, adjusted the tension.  I really can't afford to pay to have it serviced.  The service fee would cost more than the machine did.  Could someone please tell me what I am doing wrong and if I can fix this myself. Thanks.

I had a Kenmore that did the same thing. It would ruin my projects. Not sure what to tell you, except that I feel your pain. Did you try cleaning and oiling it?

Erin

Try changing your needle. Your machine might be picky about what size needle you need. I would try using at least a 90 or maybe even 100 size needle. Also, make sure your bobbin is the right size for your machine.
HTH

Thanks ladies for the suggestions.  It was working fine with the needle that came with the machine but I had to change it to a ball-point needle for a project with PUL and that is when I started having problems.  They were very fine needles.  But I think I have the regular needle in it now. 

I also bought pre-wound bobbins and they seemed to be working fine. I'm on the second one, so I don't think that is the problem.  I never realized bobbins came in different sizes until I went to use my friend's machine, which I borrowed to finish these projects until I can figure out what is wrong with mine.  The pre-wound bobbins are too big for her machine. 

There are definitely lots of different sizes of bobbin. I would be concerned both with the size but also the quality of the thread on the prewound bobbins.

I invested in about 15 bobbins for each of my machines (Bernina metal bobbins are not cheap, Brother plastic ones are) so this way I rarely have to unwind one to start a project with a new color.

Since it sounds like you have a plastic drop in bobbin, you don't need to oil it. But you should find the bobbin it came with, wind that with some quality thread (C&C as a minimum) and buy an assortment of new needles and change needles every few projects. 4-8 hours sewing time but less for layers, zippers, etc. I think that will help your sewing experience very much.

Good luck!
Erin