Make sure you didn’t over tighten your seat clamp (bolt that holds your seatpost in place.)
See “Periodic lube of inside tube” under maintenance section…unless you just changed your shims (item #42) out on the inside tube or changed the inside tube.
(this procedure can only be done if you have a 3″drop post 325mm or longer or a 4″ drop 375mm or longer) You could increase the tension of the spring pressure by turning clockwise bottom cap nut (On bottom of seatpost, Item #68) Note: It is possible that if you increase too much, the post wont be able to engage in the down position. Just check to see that it still engages in the down position after you turn clockwise. If it won’t engage in the down position, just back out the bottom cap nut until it will engage.