I have the X7, equipped with Recon Silver TKs. There is no preload adjustment as this is an air shock.
-If you look at the top of the fork from the riding position, there is a blue dial on the right which is the lockout. Use this to almost eliminate any bounce. This is great for efficient road riding.
-On the top of the left side is a small black cap. If you unscrew this cap, it will reveal a Schrader valve. Fill your shock to the appropriate PSI as per the label found just below it.
-On the bottom of the right side is the rebound adjustment, indicated by an arrow, a rabbit, and a turtle. This adjusts how quickly you want the fork to spring back after compression.
That is really it for adjustment. Simple and straightforward. Mine gives a unique "whooshing" sound when it rebounds, indicative of air shocks. I am assuming it is normal. Does yours do that?