Morning Matt, I posted a pix of that 686 on the Guns, dogs thread. I literally ended up using armor all tire cleaner on the Pachmeyers. Turned out ok, not good but just better.
It looked good in the photo.
Unfortunately I have little expertise in vulcanized rubber and what causes it to deteriorate.
Hopefully it was just exposure to fumes from fuel etc and maybe will be OK now. Time will tell.