Nos
One of my friends has just had the issue you talk about on one of his twin 4 stroke Mariner 40's, turns out there is the correct way of fixing with a full strip down and replacing parts or you cut the rubber tube just down enough that you and slide another tube over the top with a clip to reseal it afterwards. Then with a drill bit remove the corrosion, slide the tube over the original tube and seal up.
I've not done this myself, just bar talk, but quicker to do and test that a full strip down and then wait 2 weeks for the parts.
Jelly
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