Yes there should be that much play. Pull it tight fold it over the edge of the sled and snap on the trim lock. I recommend using a number 2 square screwdriver bit for the trim lock screws. If your having trouble with the trim lock you can put on one side screw a screw in and then pop the rest on. Hope this helps. If you have any other questions feel free to ask.
Getting new seat rail brackets will help with being bent (im assuming thats the bent part) and yes they are tight. Holding the seat rail while locking the seat slide base will solve this problem and should make the seat slide bace loosen up. Contact otter at 1800 go otter or http://www.otteroutdoors.com for the seat rail brackets. They should b covered under warranty.
Kevin. Some of those 650 canvases were a little small. The poles to the left and to the right of the seats need to be drilled out. The pole that goes in the L pipe above the seats need the push pins need to be moved down a half inch. This well loosen the canvas allowing it to rest on the ground.