it is in the dungen cell.
The fuel rod powers the saucer Excalibur. The hovercraft runs on manure.
no
When you get a replacement for it, it automatically snaps into place. (see the related question)
You have to get the fuel rod
go to the mill and get the ship
The new rod that is not broken will be at the bottom. Click and drag the new fuel rod on top of the of fuel rod.
You don't refill it. There is a replacement fuel rod in the captured robot invader in the castle dungeon, and you can reach him through Mordred's underground lab. (see related question)
The saucer Excalibur is crashed in the mud to the right of the old mill. It will need a replacement for its damaged fuel supply, the green fuel rod.
The crashed saucer Excalibur needs a replacement for the broken green Fuel Rod. You can get one from the robot invader in the dungeon. (see related questions)
You can't fix or refill the broken fuel rod. Fortunately, there is a replacement that is powering the imprisoned robot invader. Go back to the dungeon through Mordred's secret laboratory, and you can get the replacement rod with the help of the robot owl Merlin. (see related question)
You get the replacement green FUEL ROD for the SAUCER Excalibur from the robot invader in the dungeon. (see related question)
You go to items, and you drag the fuel rod into the place of the broken one. It should power up.