That is the bottom of the driver's seat. The way it is now, it's like sitting in a rocking chair and if you lean too hard on the back then the metal tube along the front pulls through the open hole. Then the seat is always reclining.
I've read numerous posts and this seems to be a common problem. That metal holding the seat on to the slider frame is pretty thin. It seems that some people are able to weld new metal into that spot and it holds. While others have opted to just replace the seat altogether.
Sometimes "Run To Distruction" is the appropriate trouble shooting technique. ~ CCKEN via Cherokee Technical Forum
Utah Jeep Forum #149
1998 Black XJ
1995 Green XJ -- rolled n sold :D