Geez I hate those yellow stains.
But on a photographic note I did lots of newpaper work in the 70's and we used an Ilford B&W stabilization processor. All of my old prints that I kept from that machine have turned yellow. I do understand however that the prints from this process were never meant to be permanent. However prints that I made using the usual processes are still looking great.
You might be able to tone them and just tell everyone you thought the funky blue was really cool in the 70's. LOL