The root you're worried about is the best root visible, the others are questionable. I think a repotting is in order just to see what the rest of the roots look like. Are there any drain holes in the glazed pot or is there another pot inside of it? Could be poor aeration of the root system.
Check out youtube, there's lots of repotting videos there. In short you need to get an orchid bark mix that's suitable for Phals (e.g. pine bark), pull the plant out, remove the old potting mix and any dead roots and pop it back into the same pot with the new mix and give it a good water