I have a Sony Trinitron KV-27S42. The screen is rotated slightly counterclockwise. It isn't terrible, but definitely noticable (about 1/2 inch difference). I have been in the service menu, but there doesn't seem to be a setting for this like I have seen in the newer/higher model Sonys. I have also looked through the service manual, but there isn't any clear mention of rotating the screen. There is mention of things like "beam landing", "purity control" and "deflection yoke". As you can see, I am no expert with CRTs.

Any ideas how this can be fixed?

You can probably fix this by tapping the yoke *very* slightly, but I don't know if you want to mess around the back of your TV. People can be understandably squeamish about this sort of thing.

I guess my question is:
The "yoke" seems to be the only thing easily adjustable inside the case that might affect the alignment. Would rotating the yoke rotate the screen?

Your post appears to answer this with a yes. It doesn't seem that difficult to remove the case and rotate the yoke a little. I wasn't sure if the yoke actually rotated the screen or if it only dealt with convergence, as the service manual only mentions the yoke in regards to adjusting convergence (I think!).