Fourth being the second from the smallest.

The derailleur seems normal in all respects. The chain is feeding onto the freewheel with no obstructions and it is free in its movement. That is what puzzles me.

OK, I'll bite.....how minor was the surgery? I'd like to keep this one as original as possible, but maybe I'll try it.

I will also try yet another wheel and freewheel combination this weekend. One that is off of my Raleigh International that is known not to skip. I may even try that chain, too.