You are on the internet on this forum - which is a treasure trove of information.
$1400 will go a long way towards getting you educated instead of you paying through the nose year after year..
There are any number of videos and books on basic maintenance of engines , boat maintenance and so.
(diesel or gas - changing a filter is changing a filter , not rocket science)
There is/was a very popular TV series on maintenance of your boat, and on, and on.
Don't let anyone snow you (or BS you) by blabbering on about the complexity of maintenance.
An oil change is, replace oil and filter. See a video, do one - and suddenly you are an expert.
Same for the fuel filter.
(I just watched the mechanic on a ferry boat change one. He can barely talk a coherent sentence, a rocket scientist he is not, yet he did it in about 10 minutes.
To do the 400 hour check there are a number of steps, but each one is a discrete item and does not have to be done all at once.
Mike (Illusions) has been to a diesel maintenance course (not changing pistons and such, just maintaining the engine.) He found it to be interesting and fun (if not, he will correct me with a slap along side the head)
For a $100 some local diesel mechanic would give you two hours of his Saturday and lead you through the basic steps of maintenance.
On most boats changing the impeller is usually the tough job simply due to being in an impossible place to reach. You could throw in an extra fifty bucks and have the show-and-tell mechanic do that one while you watch :mrgreen: