anything that has oxidation on it, be it copper or aluminum, soak your blocks/fittings, etc in 5% distilled white vinegar (sold at any grocery store) for about 6-12 hours, then take a toothbrush (I prefer a soft metal bristle brush) and scrub them down while submerged in vinegar. This should remove most if not all of surface oxidation that often happens with copper and aluminum. After the vinegar, give all the parts a bath in 70-90% isopropyl rubbing alcohol, and you'll be good.