How to expose 84-011 roller

First, you must remove the screen wire and spline. After that, unscrew the adjusting screws on the wheels to allow the rollers to re-track. Hopefully you can pull the frame apart to reveal the corner wheel. If not, look at the channel of the frame and see if there are indents locking the corner into the frame. If that is the case then you will need to drill them out to release the corners.