I found a nice YouTube video(Clean injectors on Yanmar Diesel.mp4) which convinced me to take them to a local diesel injector shop. They rebuilt them, new copper gaskets, o rings etc and bench tested to ensure the spray was correct. That cost approx. $55 for both.Now I know they are good.
I still have black smoke when I get up to about 2000 rpm. So, the trial and error continues while waiting for the shop guy to fit me in with his technical expertise and make the smoke disappear.
