Sometimes new trucks and a hefty clean-out of the tracks does wonder... even though it doesn't look like there's anything there to clean.
Sometimes there's a spacer strip at the top that you can remove, and then lift the door up and out.
Our spacer is a long black plastic thing, and I had to unscrew the visible screws first, then move the slider to expose the screws on the other side, unscrew them... then move the door back and pull the spacer out from one direction. After that, the door would lift enough to clear the lower track.
FWIW, I was able to reverse the trucks on our sliding screen; moved upper to lower and vice versa.
Otherwise, sliding door trucks are said to be semi-standard in size, Home Depot may have what you'd need...
Oh, and sometimes the overhead structure can be sagging... which could put a crimp on sliding doors, too...
South River, Chesapeake Bay