David, I'm wondering if a lower concentration of sensitizer in the glop might help limit staining, even though it would probably increase contrast and lower speed. Less dye hopefully would mean less staining. I'm also wondering if a pre-soak (prior to clearing) would help clear more of they dye stain.
Also...did you check to make sure the table salt you were using was non-iodized (& that there were no other additives, like to prevent clumping)? I don't know if any of those things could have interfered with the clearing process.