There are several threads in the archives for this -- MIMF (Dale) has posted some excellent instructions on line as well.
That said, basically run your slide out a bit and underneath you will see two carriage bolts with locking nuts. You want to loosen the locking nuts and then move then down just a little bit -- a little movement makes a big difference inside so make small adjustments. You may have to have someone inside bounce (jump) up and down a bit to have the slide move; then run it in and out a time or two to check the adjustment.
As I said, Dale has some excellent instructions posted and hope you or someone can find them. I'm on a slow connection so I have to apologize for not finding the post already
. Best of luck.