I will describe the procedure I went through which is also in the operators manual. If you don't have the operators manual you can view/print it from the website Demco Products
Your issues may not be the same as mine which is why I suggested to call Troy at Demco but here is what Troy advised me to do to eliminate my chucking issue. My issue was significant chucking when making a turn like in a residential area. The chucking was so bad it felt like it was going to jerk the truck right out from under my butt.
Stand at the tailgate of your truck and look at the gear with teeth there is a flat bar that comes out from beneath the gear towards the back of the hitch. This bar must be straight if it is not then take a crowbar and move the bar until it is straight. This should put the hitch back in time and the hitch head should then be straight. Next you need to adjust the hijacker autoslide gear adjustment bolt which is located at the cab end in the center at the bottom of the hitch. The bolt has a lock nut and takes a 1 1/8 inch socket. Loosen the bolt and lock nut. After loosening the bolt tighten it in BY HAND until it is tight against the gear and then back it off 1/8 of a turn and tighten the lock nut. After this adjustment you should have little to no for & aft chucking when starting and stoping in a straight towing position.
Next I adjusted the capture plates which are the guide bars on each side of the top of the hitch head. These capture plates guide the pin box in and go against each side of the pin box. First measure the width of the bottom of the pin box which slides up onto the hitch head. Loosen the bolts and lock nuts on the capture plates and adjust the capture plates to the width of your pin box plus 1/8 inch. This will leave 1/16 inch on each side of the pin box when between the capture plates. Finger tighten each bolt. Make sure each capture plate is an equal distance from center of the hitch head. Next hitch up the 5th wheel in a straight position. Then get into the truck bed and push the guide plates against the pin box and tighten. This will eliminate any slop between hitch head and pin box and should eliminate almost all chucking when making turns in say a residential type area.
These adjustments eliminated my issue and I now have little to no chucking towing in a straight line or while making turns and I feel the hitch is now operating as it should.
Feel free to call me if you have any questions.