I am needing to change bathroom sink faucets, found a really nice widespread 1/4 turn set. I have now identified as Harden. Finally / carefully now have removed the stems. I see one o-ring washer was bad. Been cleaning, soaked in vinegar to clear water deposits. I still find blue deposits. On the two brass bodies, stems removed, I tried acetone. It still has blue internal deposits and other crud. So #1, what is the best way to clean this gink out? It's inside hard to get to. I will get new o-rings, figuring they are "standard sizes. What confuses me is that there is a blueish "paste" above the ceramic valves. I see it in the 1/4 turn stop or motion limiting groove. Is that supposed to be there?? So, #2) Should that "paste" or residue also be removed? What fluid would work best? Or is it supposed to be there, what is it?