I started taking my sickly looking phals to a local orchid shop. The guy will look at it and either repot for me or tell me it's fine. This works out a little better if you only have a few plants and don't want to end up with a huge bag of potting medium. The danger, of course, is that you will enter the shop with 1 or 2 plants and leave with 4 or 5! I am sure that is why the shop offers repotting services!