At the Puzzle Door of Mordred's castle, you have to press 10 of the 20 tiles just once to flip them all over, but you can only press a certain 10 tiles.
Press all four tiles in the 2nd row.
Press the middle two tiles in the 3rd row.
Press all four tiles in the 4th row.
If they are not all turned over by this, reset by leaving the puzzle and starting again.
You can't. That only happens at the end of the game.
You go into Mordreds lab and grab a paper and turn it into her.
56, 52
You first get the manure then you make the mill turn right then entert the top and go to your bag and hit use on the manure
The mill gears on Astro Knights Island are in the second-floor loft of the mill, and they are locked to prevent the windmill arms from turning. Grab the short hanging rope to unlock the gears. Go outside and turn the windmill arms counter-clockwise by climbing on them, and you will see the roof dome open.
The gears in the mill on Astro Knights Island are locked by a small catch on the inside. Pulling on the attached rope unlocks the gears and then you can freely turn the windmill arms by jumping on them. (Turning them counterclockwise opens the roof dome where the hovercraft is stored. Adding manure will send it over to the mud swamp where you can use it.)
The coordinates are X-56 Y-52. You can add them after you replace the damaged fuel rod. (see related question)
Go inside the mill and pull on the rope that releases the gear lock. Now the arms of the windmill will turn. Go counterclockwise and watch the roof dome.
Inside the windmill, climb into the loft and hang on the rope. This will release the gear lock and allow the windmill arms to turn. Jump up on them to turn them counter-clockwise, which will open the roof dome.
You can't get the hovercraft from inside. Unlock the gear lock and go outside. Climb on the windmill arms and turn them counter-clockwise. This opens the roof dome.
To get to the hovercraft in the attic of the mill, pull the rope to unlock the gears. Then go outside and turn the windmill arms by jumping on them. When they turn counterclockwise, the roof dome will open. Add manure to the hovercraft and it will go to the swamp.
Once you have opened the attic dome, you can add manure to make the hovercraft work. To open the attic, release the gear lock and turn the windmill arms counter-clockwise.