Ok. Had the pump off. It is still like new. The car having had a new ?stat, rad, & fan It is felt that it is time for a new head gasket. I suspect that air is entering the system and forcing out coolant, causing locks etc. I have just changed the head on my 6cyl Nissan Jeep which did the same thing. IT has an expansion bottle so I could see the bubbles....
The view through the pump mounting is of a VERY clean and un rusted cooling system. The engine is at around 100,000 miles so a new gasket will do it no end of good.
I'll keep ya'll posted , and thanks for all the sensible replies.