Why?
 

For months and months I've quilted using the same big cone of thread and a size 12 needle. For the past 2 days, I keep having skipped stitches. I've changed out the size 12 needle, no difference. On a whim I switched to a size 14 and the skipping has virtually stopped.

Why??? I am not using a new pack or a different brand of size 12 needles. Same package as always, I bought many packs in one batch so essentially the same needles.

Same thread. Same quilting cottons.

Can tension somehow make me need a larger needle? Perhaps something changed there? What else could it be?

I've solved the problem but I need to know - why??

I find it's usually because I either have lint in my bobbin case, especially in that tiny little loopy thing that you have to catch the thread in, or else sometimes there is a tiny burr on the bobbin case. Try cleaning everything top & bobbin really well and oil your bobbin hook. If it's still an issue, I'd make a service appointment.

Ok, now things are really odd. I did as Bree123 advised. I opened up the bobbin area. It had more lint than I expected, I usually keep it spotless. I cleaned it and put a drop of oil on the shuttle run. I did the "yo yo" test on the bobbin case and found it had gotten tight so I loosened it up. I put a drop of oil on the bobbin post and reassembled.

I put my size 12 needle back - still skipping stitches. If you remember, this was my 2nd size 12 needle. I did not discard the first needle since I wasn't sure it was bad. I simply set it aside. On a whim I put it back and now everything is fine. What???

The needle I'm now using is the first size 12 needle which I replaced because of skipping stitches. I just don't understand. I've discarded the replacement size 12 needle and I've just sewn 4 WOF strips with no skips. Odd huh?

Life is a mystery...:)

The only thing I can think of is that you are not inserting the needle all the way up into the shaft. Turn the power off, loosen the screw enough so the old needle falls out, insert the new needle using your fingernail or the old needle with the tip inserted into the eye to make sure it's pushed up all the way. If the needle is even a tiny bit long, you will skip stitches.

Princess, that's an interesting theory. Perhaps the first needle was inserted incorrectly and the 2nd needle was simply defective. That would explain it all.

Or ghosts. Ghosts would explain it all.

I would have said lint

Perhaps the needle had come a tad loose and moved, either down or twisted