How do you adjust the preload on rear Vforce shock.

I can see the notched rings to rotate to compress the spring but can not get a tool in there to do it.

 

Long Screwdriver and a hammer will work fine. Just hit the top ring so it will loosen. Once it is loose put the machine up so wheels are off the ground and spin the bottom ring until there is very little tension on the spring. IF you go too far the spring will move to the right and left when you jump. This will ruin the shock I'm told. Good luck!