OK 4th time is a charm! Yep we had to remove the heat exchanger tube stack(TS) yet one more time.
We were going to replace or at least inspect the impeller and loosened the cap for it.
What came out? Antifreeze came out, oh no!! Yep, and so there you have it. The raw water and fresh water were possibly mixing which I think they are but at least the fresh water (antifreeze) is mixing with the raw water. So it was either the O-rings were not sealed ot the TS was damaged.