There should be an Allen screw through the filter adapter, but it is kind of hard to see. If I recall, there are qty=3 o-rings that need to be replaced at this time
When mine started leaking, I took it off, cleaned it and the flange, took out the o-ring, and applied blue rtv to the o-ring and flange and tourqed it back down. Let it sit till the rtv cures. It fixed mine.
Yes, just go to the dealer and pick up the 3 o-rings for the oil filter adaptor. It not hard to do. I think it cost me less than $10 for all 3 O rings, nice to know you have the right ones on hand BEFORE you start the job.
There is a write up on www.madxj.com showing how to change from the pre 91 oil filter adaptor to the 91 & later version. It has good pictures and once you read that you will be ready to do the work yourself.