You can try cleaning the mast and waxing it to see if that helps it retract all the way down if not when I replaced the antenna mast assy on my 96 convertible I found it easier to remove left rear wheel and inner fender and left outer tail light assy for access also pull up carpet left side of rear compartment to get to body plug. If I remember correctly the mast cable from GM cost about $25 and a new assy from Mid America cost $149. To replace the cable you will need to drill out the rivets to take it apart and reinstall with bolts and nuts.
Thanks for the info source and ideas. I got the new mast installed and it seems to work, most of the time, but still wants to leave a couple of inches sticking up once in a while.
I hate the idea of replacing the motor and all. I think I will just unplug the motor, in the down position, if this doesn't improve with lubrication and running it up and down a few times.
I did that. Cut about 2 inches off the end of the ribbon. It didn't help and I am reluctant to cut off any more. It will go all the way down if I gently push it while it is retracting, otherwise, it leaves about an inch or two sticking up.
I had the same problem. In my case, the plastic end with the teeth
broke off, leaving a few inches stuck in the drive. I had to
remove the entire unit from the car, and open it up to remove the
broken piece. Takes about an hour to take it out and put it
back in if you follow the instructions in the shop manual.