After looking at your excellent diagram on line, I figured it out. For others out there with the same problem, all you need to do is release the gray lock by sliding it to the right using a small slotted screwdriver. Then just give a downward tug on the door and it will pop out of the upper half that houses the adjustable bolt. Slide the door out of the way so you can access the hardware. Use a standard wrench to adjust it up or down by turning it clockwise (up) or counter-clockwise (down). Now slide the door back under the hardware still in the track, and lift the door up. Now pop it back into the upper half. Slide the gray lock back to the left to secure it in place.
