OK. The solution to the tach cable problem. Took the old cable in to the dealer's parts section. They had ordered a new cable and we compared the two new cables and the old cable. no discernible difference except the new cable was an inch or so longer. I only had the housing for the old cable so we could not compare the actual cable. I had thrown away the old one.
Parts manager suggested that the housing that connects to the engine case might be striped or damaged. That's part no 290 in the drawing above, hour meter And I might need to order that part at $100+. I decided to take the new cable they ordered and try it. It had the same problem, would go on ok for a few threads and then pop off. I then removed the part at the engine, Part 290. Of course it was difficult and no room to get to it, but eventually it came off. Tried the new cable - no work. Then i looked inside the part and saw the part the cable actually connected to. It had a male flat part rather than a female part. That meant the other end of the tach cable would fit there. I had been trying the wrong end of the cable the whole time. The parts manager also. He didn't know either. I had previously tried both ends of the old cable housing and the so called correct end did not want to go on wheras the other end went on easily and fastened down tight. So I thought i had the right end.
So I reinstalled the hour meter part to the engine. and connected the new cable correct ends. Finally everything was connected and I started then engine and The tach worked perfectly.
More than you wanted to know probably. After you work on something and finally find that the solution was simple rather hard like you made it, you feel rather stupid. But I know how to do it if it happens again.
