Well, I'm sure you are all waiting with baited breath for my further findings

I started by pulling off the intake line to the water pump, just to be sure there was good water there at least. On this boat you can do that without a flood as the water level is about 4-6 inches below the pump. I stuck a snap style bottle stopper in there (perfect fit). Pulled the cover off the Oberdorfer to check for broken vanes. All perfect, like new, but the last 1/2" or so on that intake line had a split in the rubber casing, so I shortened it to get a clean connection. Started the engine but did not see a water flow change as far as I could tell and the engine got warm pretty fast so shut down and attacked the HE. I reasoned that since no impeller junk would be found at the input end, it made best sense to start at the output end; heck it's 95 out so I wanted to move things along here. The other end of the HE was not pretty and the same thing another of our owners described: Pieces of anode and residues and in my case also
about half of a complete anode!!! Unscrewed the working anode, checked it (looked good and no coolant came out, so no internal damage most likely) and left it out to use the area as a drain hole and flushed the end area with a very slippery detergent my company sells. Replaced the anode, closed everything up and fired up the engine. Immediate difference in water flow and engine tone (not to mention a pant load of suds!). The engine noise changed also, less "gargle-putt-putt" and a softer water gushing sound. Am I done? Jury still out as I could not take a full run and can't for a couple more weeks, but things are certainly not going to be worse and I am guessing better to ok when the run comes. I do think an HE ream and vinegar saturation, let stand and flush, etc. would make sense and I will put a new impeller in soon. A couple of observations: I recall the OE heat Exchanger had a cap at only the intake end. The unit I have (Mr. Cool brand nickel-copper model) has caps at both ends, a huge plus, no? The other thing is the pump impeller. About half the vanes as the Sherwood I had before, so if you lose a couple I am guessing you are going to pump less water than if two are gone from a Sherwood. You guys helped me a lot on this one so I hope this report pays forward to someone else. In a couple weeks I will try to come back with my new running temp numbers.