Phal Re-potting with possible root problem

[labyrinth1959]

I have a Phal that was re-potted a year and a half ago. It is quite large and just completed 6 months of blooming. I am wondering if I should re-pot it again. My concern is that I may have put it in a pot that was too large (6") because it had a wonderful root structure before I potted it but there has been no sign of root growth in the potting medium since. In the mean time there is a bevvy of root growth above the medium...8 new in the last six months. I am worried that all the roots in the medium are rotted and gone. if that is the case, I am not sure how to re-pot with no roots below the surface and whether a smaller pot should be used. Suggestion would be very welcomed.