how to adjust sliding patio door with adjuster on side of slider mounted with 2 side screws and top spring loaded screw

I have a sliding glass door and a fixed door ( about 6 years old) going to my patio which was purchased at Home Depot to replace the fire damaged ones. It was probably the least expensive doors made and is either white aluminum or vinyl. As you look at the slider from inside the house (slider is on the inside) there is a white plastic adjustable block attached to the bottom left side of the slider directly over the channel track. There are 2 screws attaching the block to the door and a single top screw which appears to be spring loaded. I need to raise the top right side of the door about 1/8- 1/4 inch and when I loosen the two screws the bottom of the block rubs a small plate in the floor of the channel and the spring loaded screw is already fully tightened. How do I make the adjustment I need. Thank You