Yesterday, I was looking at a machine that was giving a customer problems. Here and there under the fabric, she got a tiny loop of top thread. Since she had told me that she put in a new needle, I looked at a number of other things to solve the issue. Everything checked out o.k. I put in a new needle and bingo, all was good. Even new needles have a certain percentage of defects. So, sometimes, it's worth it to at least try another needle and see if it makes the difference. Cheers!
P.S. A new needle, means one out of the package, not one out of the pin cushion!!