I bought a used 980 TI Hybrid from a friend knowing that I may have to refill it unit due to permeation.  May be even replace it with a kraken G12 and a New compatible AIO cooler.  Before he had the card, he bought it knowing he may had to this too. He never got around to it so I bought from him.
 
I installed the card into my machine to confirmed temps and it was idling at 70c and game play would jump to 91c.
Installed Geforce Experience, I believe is at latest and it installed latest drivers.
 
I took apart card, clean thermal paste off GPU and copper plate with 91% isopropyl alcohol.  Saw that the screws holding the copper plate looked a little warn/stripped but was still able to take screws and get copper plate opened. I then cleaned and top the cooling system with distilled watered making sure to shake radiator to get bubbles out.  Put everything back together and card back into system.  Idling temps are now 60c but my game play temps are still at 91c with Fan revving at max speeds. It does not drop below 91c when I am in a game. Attempted a custom fan control with MSI after burning having fan rev up to 100 at 70c and temps still jump to 91c.
I don't Air flow for system should be a issue since I am currently running it with no side panels.
Games I tested were Halo infinite, Destiny 2 and Shadow of Tomb raiders.
 
I've already order a AIO and planning to pick up a Kraken G12 from Microcenter when AIO comes in.  I'll replace that once that comes in.
 
That's the back story and now for what I am looking for and might end up doing.  May be some advice will help to.
 
I might do DIY project and replace RAD and Tubes but keep the pump after I put in the Kraken g12 and new AIO cooler.
I can probably figure out Tubes and RAD but can't figure out what size screw is used to hold on copper plate that seal in Coolant to pump.
Since the screws for copper plate is worn/strip I'm afraid to reopen it with out replacement screws, so I was wondering if any one knew what the screw size was?
 
Any advice on what I can look at doing to get temps down with out replacing part would be helpful too.