Bedroom slide bind

[routemaster]

I have a problem with my bedroom slide by the box is in a bind in the top left and bottom right corners, it has shredded the wipes. The best way I could check is the header and sill are parallel but have a run down to the front, the king studs are vertical to the frame.
The box is square,
I thought about shimming up the rollers 1/4'' on the front one then a 1/8" on the center one would lift up the slide box floor to take it out of a bind. Or the other thought was to use roller runners on the underside of the floor. What would you do?
Make sense?

[egwilly]

Which brand of slide is this? Rack and pinion type or Schwintec?

[routemaster]

Wire pull.

[Jkjavelin]

With cable slides it may be that it's out of adjustment, but I've not heard of it getting caught because of it being that bad. Measure the 4 corners (slide to main wall) to see how square it is. Hopefully you don't have a structural problem with the sidewall frame, causing the cutout to be out of square. The front overhang area is susceptible.
JK

[routemaster]

I used level as a datum plum and see the readings top and bottom. Can not see how I can check the cut out for squareness, the sill an studs are covered with a cover can not check the welds.
As an exercise I jacked up the left corner and would need .4" shim to get the wall plumb!!