catherine96821:BINGO...I called.
I need shorter clips.
which I found in the box.
I bought two expansion rings, I only need one. Ikelite no longer sells the dome port assembled with the ring. (like mine was) Now, they are sold seperately. This has contributed to some confusion, they say. They also said it takes two people to unscrew the dome. They volunteered that, so it must be an issue with more than just you.
If you've been using your thighmaster you can do it by yourself. Hold the dome (with the cover on) between you knees. Then you can use two hands to unscrew the port body. Worked for me.