Update, after a lot of messing around. I rebuilt the carb, found the bowls had warped... (not causing the problem), the needle wells were leaking as the glue had deteriorated... (part of the problem). Got a new bowl, rebuilt the card, still had starting problems though. After a trip, and wanting to work on another problem it developed, I couldn't get it to start. On a whim, and past experience... I swapped the ignition module. THAT seemed to solve all the starting problems. I've had ignition modules go bad before, but never partially bad. They either worked or they didn't. Anyway, after switching the ignition modules it has been starting just fine ever since.