I removed skylight, cleaned channel and put caulking product called 5200 than reembedded skylight. Almost 10 years now no leaks. 5200 available at West Marine.
All good comments TandE. One more thing is behind impeller is a plastic shatter coupler. Meant to break if engine is under stress. Usually yellow plastic. Check it is intact.
Ask owner what they do after each outing in salt water. They should be flushing the engines. If a fresh water flush kit is not already installed then install on each engine. Perko seems best.
