Not sure why Jens thinks that the reversal exposure causes the yellow stain. His PDF file seems to change quite frequently, as he adds more info.
Re-exposure using a bright bulb is common to most published processes, see (there was a url link here which no longer exists), and I've used quite a few over the years and never had a yellow stain.
I would increase the wash time after the Bleach bath and give good agitation while washing, same in the Clearing bath, again give a good rinse, do this in the dark.
Ian