Volkswagen Repair: huge oil leak on top of filter assembly, vw repair, filter unit

Question
1986 cabriolet started leaking oil from on top of oil filter unit. i have a new gasket for same,but i wonder how much disassembly is required? i dont see any way to replace the o-type ring and i wanted to know how to go about this job

Answer
As you can well imagine you are telling this to someone over the phone...no can see....if yer not sure, go to the library and thumb thru the various vw repair books until you find what you need to see  5 minutes read will do a world of good in helping you.  Not all publishers are the same in repair aspects.  Does not need to be the same year of book, just approx.