Thanks for the information Ricd about the injectors. My MD2020D was new in 2002 and I doubt if the injectors have ever been checked, serviced or given so much as a second thought until I bought the boat in 2010. I’ve had it professionally serviced three times since then, and done the intermediate oil, filter, antifreeze, cooling water impeller and fan belt changes etc., myself. None of the professionals suggested doing anything with the injectors despite specific questions from me, and the latest comment about leaving well alone was from an engineer last winter during the lay up. The engine does run smoothly, it is very economic, there is no white smoke at all, and yesterday Friday 13th came and went very quietly and without hiccup. 💤