So the damping rod had fallen down into the hydrolic chamber. I know this because I have zero patience and took the bike apart. Before doing the repair the only idea I had about the shock was from the service manual schematic.
In hindsight I should have taken more pics or filmed what I was doing, so sorry I didn't! I was too focused on fixing the shock right away.
The access wasn't as hard as I thought. Just have to remove the thin side panels (the same one to remove to access the air filter) on both sides. Then the battery cover and the front panel (in front of the valve cover). Then the seat, trunk, and trunk support, and the rack (allen key).
On the inside under the seat there's only 2 hex screws, one on each side, holding the plastic onto the frame. The hardest part is the plastic tabs holding the plastic body to the floorboard. The whole rear section of plastic lifts off as one piece. There are a few wire connections like the seat key cable, so I didnt lift it off far, just enough to move to the side and rest on the frame so I had access to the top of the rear left shock.
The thin metal rod that runs to the top of the shock is actually supposed to be threaded into the top. Mine had came undone. The shock itself was easy to remove from the frame, just two big hex bolts. So now I have the shock in three pieces. The top which the rod screws into, the spring, and the bottom which has the adjuster and the cylinder and the rod.
This was not an easy fix and extremely dangerous to do without a spring compressor. My uncle was with me and acted as the compressor. First with the shock apart, I pulled the rod out as far as it would come. There is a nut on the thread at the top of the rod. I tightened it to expose as much thread as possible. We secured the bottom on top of a brick with a no slip pad. He crouched over it with the spring, and used his bare hands to compress it. As soon as I saw the thread from the rod come over top of the spring I screwed the top piece on.
To tighten the top piece onto the rod I had to hold the rod somehow as it rotates freely. I didnt want to scratch the rod (we already scratched up the spring trying various vice grips to compress it from opposite sides, this is where it was dangerous). I used a shoelace, threaded through the spring, wrapped around the rod. Tied each end of the lace around a pen and tightened the lace around the rod by turning the pen repeatedly. It worked well to hold the rod while I tightened the top, getting two and a half rotations of thread. I then worked the nut back up the thread to the top of the rod.
