Well, thanks to all of the advice here my CX is back in business.

I decided to take apart the rotor and see if I had somehow missed the holes. Once I removed the lower roter head, I saw that the shaft did have holes but..... (wait for it).......the lower rotor head's top two holes did not go all the way through. Both top screw holes were blocked by plastic. Not only did this block the holes, but it kept those screws from ever coming in contact with the shaft. I didn't pay attention to the holes when I was changing the rotor heads and after it was on, it was hard to see.

So, a pretty dumb mistake on my part. Like a lot of problems, the answer was simple but the process of finding it was long. Once I drilled out the plastic, the rotor head mounted correctly, which in turn locked the swash plate in place. The CX is flying well.

On the plus side, I did learn a lot about the CX. I took apart every piece along the shaft, so it was an education.

Taffey, thanks for the input on the flight time. I do have training gear on so that is probably contributing, along with the altitude.

Thanks to everyone for the suggestions. It gave me a lot of insight into troubleshooting the CX.

EXW