I see a bunch of postings about broken power antennas so I dredged out this email from 2 years ago that I sent to somebody else. Maybe some of this will help, especially the part about repairing or replacing the inner core. If the motor runs endlessly but the antenna will not go down, it'* because the flexible nylon inner core is broken.
I know someone posted part numbers for a replacement mast (only) from GM for $12 or so, but I would want to be sure that that includes a new _core_, not just the metal outer barrels of the antenna.
>Has anyone rebuild or taken apart and inspected one of the
>GM antenna units used in the 80'* on Toros and RWD Olds'?
I repaired the one in my '93 SSEi not too long ago and I imagine it'* the same as those. I was going to write up a detailed summary of the whole process but never finished it; I still have it somewhere on the laptop...
>The one I have on my '81 D88 works, but since I have the
>fenders off, thought it might be good to do a little
As far as PM goes, I would check that the drain hose is clear so that rainwater getting in the top won't sit in the reel assembly, and make sure the mast stays clean and straight. Some people swear by using graphite or light oil on it; the factory manual says only that it should be kept clean. In any event, if it looks like any of the outer segments of the antenna barrel are getting hung up, do something about it before it gets worse.
When the antenna extends, a motor unwinds a flexible nylon core off a reel that pushes the tip of the antenna up, pulling the outer barrels along with it. When it retracts, the motor turns the other way and winds the core back in. It stops when it hits a limit at either end (the barrel is fully extended, or the tip retracts until it hits the fender bezel), and the deflection kickback shoves the motor slightly up or down to open one set of a pair of contacts.
When mine broke, the core snapped near the inner end where it attaches to the reel. The nylon core has a metal wire in the center. The nylon cracked with age, rainwater got in, and eventually the wire rusted and broke. The motor then ran endlessly (> 12 hours!) until I finally noticed it and pulled the plug.
Because most of the core on mine was still good (and a replacement antenna was >$100 and a replacement mast core alone was not available), all I needed to do was cut off the broken core stub and reattach what was left to the reel. The attaching point is reinforced within a curved piece of tubing that looks like a piece of antenna mast, where the core meets the reel. I couldn't get the broken stub out of that to reuse it, so I stopped by the hardware store and bought a piece of aluminum tubing in which the core would be a snug fit. I bent the tubing into a curve to fit the reel using the lid of a Gerber baby food jar. It then fit into a hole in the reel, I bent the end into a hook with needle-nose pliers to hold it there, and put it all back together. The antenna is now about 9" shorter than it used to be but the reception is still pretty good. I did this in 2000 and it'* still working today.
Point of interest: The motor housing is not only clipped but also riveted together; you'll need to pick up several small nuts, bolts and lockwashers for reassembly. Have fun...