I think the most important thing we can do for our machines to show we love them is to clean out the lint
- no compressed air though, as you found out unfortunately. cans of air can also mis-align sensors (like the thread sensor) and the cutters. It's unfortunate that you lost a board before you found that out.
Vacuums can create a lot of static and electronics don't like that - make sure it's off before you vacuum and you should be fine.
$160 for a service? Wow. I'm SO undercharging!
I wish some of the machines were more friendly to get into. That whole part under the hook should come apart so you can brush out the lint at home - without having to remove the base and then have an unbalanced machine that could tip over!
I do find some machines seem to hold all the lint in one spot and others let it wander around. There are pluses and minuses to both build methods though.
I will have to look at my cousin's 15000 the next time I'm over there. I don't recall what its attachment looks like either. I have a love hate relationship with the 350E's attachment arm. I think it lets alignment problems happen if you have to remove the hoop sometimes. Of course, most of that is solved by having a full bobbin when you start.