In F6 they are what I could best describe is 'lightly' indexed. Its like its only half turned-off. In my searching I've come to find that what I'm feeling on the F6 setting is what's expected, and I'm also seeing plenty of reference to the ability to modify these shifters to remove the indexing completely, but no mention of how.

The only thing I can imagine is that it has to invlove getting this little circlip underneath the main screw to come off. its really small.