Whole thing, at least for me. Actually, if you just loosen the T20 or T25 torx bolts from the frame (don't remove the track yet), then pop off the end caps (pull the locking tab up and pull out of the track), that will work. But you have to break the silicone seal around the bolt holes for the tracks so go ahead and take the whole thing off.
When putting the end caps back on, slide the inner tab in place first.
I use a dab of silicone around each bolt hole and at the end of the bolt before putting the trays back on top to seal it correctly.
Nothing like working all day Saturday. Yuck.