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?