Oil in spark plug well

[mxzxrider]

I bought a used 1996 960 a few years back for my son. Had 150,000 miles when I bought it. Now has 220,000. Son came home from school last week and said it was running really rough and he could smell something burning. I started looking for a burnt coil pack but what I found was a spark plug well completely filled with oil. I mean filled!! I'm thinking the o-ring blew out.
Is there a good write up to replace this o-ring?
Any help will be greatly appreciated.