Fork oil spilled out. Rebound Damper Assembly is missing
According to the 2004 Six service manual, the rebound damper screws into lower casting, just like on (I think) any other Manitou fork:


  From the right leg dropout, use a 6mm hex wrench to turn the
  compression rod counterclockwise until it screws into the casting. You
  may have to apply pressure from the top of the comp rod using a long
  6mm hex to start screwing it in.


For some mysterious reason, your lower rebound compression rod has unscrewed and let the oil in the leg out. Did your fork have a rebound adjustment knob down there when you put the bike in? Was it even there prior to that? If later, there's no "lost screw" to look for. And, as I said earlier, the rebound assembly won't fit through the hole.

At the very least, you'll need to perform a complete fork service, maybe ask your local bike shop if you aren't feeling up to task (oil can be super messy). If you did lose the knob, I'd try looking for a second-hand option or email Manitou and inquire about replacement part, their customer service is great.