I hope your "intervention" went well. It's great that you have friends and family willing to support you through your issues.
I recently had an overheating problem with my Westerbeke which I solved by removing a large piece of zinc that had found its way into the outlet fitting on my heat exchanger. Very little water was coming out the back. It seems that sometimes the zinc can deteriorate at the base faster than it does elsewhere along its length -- leaving a rather hefty piece to float/roll around inside the unit. The piece of zinc had collected other little zinclets and all but blocked the outlet. This was almost impossible to see unless you got up close with a flashlight -- so look carefully.
Also, in searching for this culprit, I took the hose off the engine intake seacock and then opened the valve -- observing a two inch geyser of water. I then fooked the opening with a twelve gauge shotgun cleaning brush resulting in a ten inch geyser! Every little bit helps.