Thanks to all who have contributed to this topic, yesterday I was inspired to tackle the antenna on my wife's 02 RX300, as the antenna wouldn't go all the way up and made an awful groaning noise when retracting. I'm sharing as I believe my experience was somewhat unique from others.
First off, the nut came off rather easily. It took a while to unscrew it with a pair of needle nose pliers, but came off easily. Once off I had my wife turn on the radio and I made 2 attempts to pull the antenna out as it raised. No go. It was stuck in the metal tube atop the motor assembly.
At that point I proceeded to disassemble the right rear interior. That was pretty straight forward and shortly I was able to access the motor assembly with the antenna still inside. With the antenna collapsed I was able to remove the assembly and open the cover. Upon removing the drum I expected to see a broken nylon cable but such was not the case. The cable was in 1 piece but the teeth on the last several inches of the cable were worn off. So it appeared the gear was able to get enough of a bite to retract the antenna, with groaning, but not enough to raise it fully.
I removed the plastic retaining cover, pulled the big main gear and cut the old cable at the base of the metal tube just above the gear assembly. Then with the help of a pair of stout pliers and some twisting action I was able to remove the old antenna and promptly pitched it. I greased the big gear, replaced it and test ran the motor in both directions. No issues. I replaced the motor assembly and proceeded to feed in the new antenna. This is where I ran into a problem.
The new antenna wouldn't feed into the gears. The cable kept bottoming out in the tube short of the gear. Puzzled I removed the motor assembly and disassembled it again. I could see daylight at the bottom of the tube when looking in from the top but my attempts to feed the antenna cable continued to fail. So I got a wire clothes hanger and cutting a straight piece, probed the tube. It seemed that at the bottom where the ID narrows significantly there is a sharp shoulder that the cable was hitting. Not the best design perhaps, but with the disassembled motor outside the vehicle I experimented with different approaches to feeding the cable and found that with a back and forth twisting motion combined with up and down it eventually went through. Once I was able to get it through while still in a state of disassembly I stopped the cable just short of the gears and with a sharpie made a reference mark on the cable at the threaded top of the tube.
I reassembled the motor and installed it once again. Then from outside the vehicle, using the same back and forth, up and down motion I was able to get the cable past the shoulder. I stopped the feed at my reference mark and oriented the direction of the teeth toward the front of the car. Then I had my wife turn off the radio. When I heard the motor start I fed the cable in. It grabbed. As it fed I guided the base of the antenna into the tube and seated it. I replaced the nut and cycled the antenna up and down several times. Worked like new and very quiet!
I reassembled the interior and turned the car over to my wife. Success!
