Richard-
In working with Catalina Direct, I discovered Catalina used many different opening port designs- sometimes multiple in the same year. Catalina Direct spent hours trying to ID the correct replacement gasket for me. The one they settled on were an absolsute bear to fit into the window frame grooves. I could never find a way remove everybit of old silicone sealant from the grooves, (solvents, little wire brushes, toothpicks....) so my new gaskets were destine to leak.  I finally settled on an easier approach, but it lasts only one season;  3/8 x 3/8 adhesive backed EPDM closed cell foam available from most hardware stores. It takes about 2 minutes/port to remove the old gasket and replace with a new one. Stick the gasket to the aluminum frame. The material will eventually take a compression set and loose some sealing quality after about 6 months, but that's not a bother becuase of it's ease of replacement. 

Richard, I posted a detailed description on how to replace opening portlight seals on 8/31/2017.  It is definitely doable, but time consuming.  However, I would do it again, rather than buy new opening port lights.  Below is a link to that post which is here in the Catalina 36 forum. The real trick is getting the old silicone completely remove from the frame.  This is the rub.  I used WD 40 along with a plastic tool I bought from ACE.  I have a 2002 MK II.  If the glass isn't crazed, just buy the seal replacement kits. 

https://www.catalina36.org/forum/technical-discussion/replacing-opening-...

Rich, I have 95 with a similar problem, I have 4 new ports sitting in my basement waiting to be installed next month when I splash the boat. Over the years I have tried all the fixes plus some I came up with and only a short term win. Therefore this winter I bit the bullet and I bought new ports. My plan is to do a write up for MAINSHEET detailing process and methods. Won’t be for a few issues but aleast it finally get documented. 
Chic Lasser
MkII Tech editor
Past Commodore and VC c36ia

I also recently bought new glass kits for the four opening port lights for my 36 MKII.  I installed them just a few weeks ago following the replacement of all the seals.  It, also, was a tedious job, but worth it.  Makes the boat look much better, and still no leaks.  Much cheaper than buying new port lights.  Hardest part is removing and replacing the hex bolts in the frame.  Difficult and worthy of a few curse words, but worth it.

I was sure that my port seals were leaking. Changed them and still have leaks. It turns out the PO had changed the O rings on the dogs with the wrong ones. Ordered some from CD. no more leaks.

We also had leaking ports when we bought Slip Away.  Replaced all the o rings and still leaked.  Was looking at frame on outside and took some silicone to the seam I guess is what I will call it and that stopped it.  On the outside frame there is a seam on the short end of the window with a gap of about 1/16" or so.  Water would enter there behind the outer frame and find its way in.  Did that fall of 16' and been dry since!