gebo

I've got a rattle behind the top panel on my '98 LS400. The panel itself seems looser than the passenger side. I started fiddling with it, trying to take it off, got scared I was gonna break something and quit.

I then decided to ask you. HOw do I remove it?

Rice

If by top panel you mean the piece with the seat memory, then it does not come off by itself. The whole door panel must be removed.
-There are screws around the perimeter of the panel - unscrew all of them.
-Pop open the window/door lock switch panel in the arm rest (CAREFULLY) If memory serves me right, You should insert a flat screwdriver wrapped in cloth on the side that is toward the rear of the car. Unplug the switch assembly as well as seat memory buttons and a little foot light at the bottom of the door.
-Unscrew a large screw located below the window switch assembly.
-There is one more screw hidden under the armrest - unscrew that as well.
-The only things that are holding the door now, are push-pins(not sure what to call them). Any way, grab the door at the bottom and feel for the resistance areas. That's where those pins are located (sides). Grab the door at each location of the pins and give it a good tug.
Once all the pins are dislodged, remove the panel by lifting it vertically.