I've been using PMK for 5 years now and have never had this problem. I doubt that you could recover the stain, once it is gone. It sounds as though something came in contact with the negative.(posted 8931 days ago)There is a fascinating article by Sandy King in the latest issue of Post-Factory Photography: he has created a new developer that he calls Pyrocat-HD, which utilizes pyrocatechin and phenidone in sodium carbonate. He claims it has all the positive attributes of PMK and none of the negative--i.e., it gives greater film speed, lower processing times, more consistent staining action, and is less toxic. I can't wait to try it!