e34 95 525i oil leak behind oil filter cup housing

the1995 e34 525i has a serious oil leak coming from behind the oil
filter cup. I have to use a mirror to view it; but its leaking from
lower rear of the oil cup. There is a circular indentation or cutout
with something that looks like a bolt with a rounded off head and kept
in by a clip.... thats where the oil is coming from. I was wondering
if this can be taken apart and fixed without taking the cup off the
engine [which looks to be a big job]. And if so; what is the best form
of attack and what do I need to get from the dealer.