Trying to find an appropriate side-task for the hero

What I'm working on is actually a game, but the issue I'm having has more to do with world-building than it does game mechanics, so I thought maybe someone here might have a good suggestion.

My main character is trying to reach a floating castle. I'm trying to work out some objectives she needs to accomplish to be able to reach said floating castle.
My current plan is that first the player meets with a caretaker in the area and gets some info and some keys to access the rest of the facilities. Then the player goes to a place to restore a connection to the bluestream mana that is used to give power to all the equipment in the area. Finally, the player goes to three towers and restores some crystals or something which is used to send a signal to the floating castle, activating a manual override that forces it to moor at a docking station.
But mechanically, i want one more objective. Something between restoring the magic power and activating the towers. I don't want the player to go straight from restoring power to activating the towers; I want them to make one other stop first.

But I'm at a loss for something reasonable to do. I'd like the player to go back to the caretaker and get some more info or tools, but if that's all they were getting, then why were they not given that when they were first there?
The real reason they were not is because I wanted to pace out the info dump; rather than explaining all the details about getting the castle to moor when their focus is just on restoring power. But it doesn't make sense in-world that the caretaker didn't just tell her everything then and give her any keys he had then.
So I need some other objective to give the player between those two, so I can give the rest of the info dump at that time.

So what's something the hero could be tasked to do after restoring power to the facility, but before they can signal the floating castle to moor?

 

Yeah I know, but this was the closest I could find. It's not really plot-related because it isn't about character motives or something like that, it's more tangential to world-building because I'm trying to establish what would be reasonable within this world. Like the idea that they would have devices powered by a kind of magic that has to be restored, that's a world-building sort of thing. How they have to go about getting the castle to moor; that kind of magic/technology is an aspect of world-building.
At least, it seemed more relevant than posting this under writing. This isn't about word choice or character motivation.

Unfortunately new members are not allowed to use that forum.

I was thinking about having some of the caretaker's keys stolen and the player has to find them to get access to certain areas, but for this point I want it to be something the player can be specifically directed to go to. And if the caretaker knew where some of his stolen keys were, then he would have retrieved them himself.

A little more of the backstory to see if this inspires anything:
The whole area is a defunct mining community. It was run by a dragon (posing as a human) who was trying to build it into a thriving center for commerce. But he was compelled to leave because of a war among Elder Dragons that he was obligated to participate in, and never heard of again. The woman who was left to run the operation (his wife) got sick and the operation fell apart with no one running it. After she dies, her daughter (the main character) returns to claim her inheritance and restore the operation and fulfill her father's dream.
But the whole facility/community has been largely abandoned and fallen into disrepair. The old caretaker has been locking gates and erecting barriers because people have been sneaking in to steal equipment, resources, even the bricks from the buildings. That's why the power is shut off and things have been made inaccessible.
Also the guy who was supposed to be keeping the floating castle in good shape has decided to keep it for himself.

None of this is written is stone and I could change various aspects in service of the final product, but this is what I have planned right now.

 

Ha ha ha, that's an awesome idea!
There's some bits that don't work with what I was planning, but man, I never thought of having someone actively undo things the MC already did! I'm definitely going to save that idea.