Ok, I bought a reepair "kit" to repair my mast. I believe it plastic ribbon. My question how do I access the antenna- from under the car? Do I take the intereior panels out?

For 90-96 coupe; might be similar to other years.
Open hatch, disconnect neg. bat. cable.
Remove rear interior cover, and loosen left rear interior cover.
Remove left cargo cover guide rail and clip.
Remove left rear speaker cover, loosen carpet on left rear side.
Now you should be able to have access to the antenna lead cable that is hidden behind the harness that goes there, loosen connector.
Remove both relay connectors near the center of the car, green, white and grey wires and some more.
Loosen left rear wheel bolts, lift car, remove left rear wheel.
Remove inner wheel well, secure other side of car so it won´t roll off the jack.
Now you can gain access to the antenna, loosen two bolts (10 mm) under it, and the ground strap.
On the upper side there is also one screw you must remove.
Now you reach all the way up behind the antenna mount to pry out a large rubber grommet with the wiring and the antenna cable.
There you have it, 1 piece of corvette antenna.
Reason I do this write up, is I believe you get a better result trying to replace the mast.
While replacing the mast, put in some new grease (while you´re in there).

And, what I did "while you´re in there", was to remove the motor housing, spray the brushes with some contact cleaner and wiggle them around, so they move freely again.
Then you don´t have to go through the hassle again when your antenna decides to do a no go similar to "I don´t hear the antenna motor but the relay is OK".

Do whatever you wish with this info...

that just happens to be where I installed the pump for my water injection

take a look you can see the connection for the antenna

[IMG]http://i242.photobucket.com/albums/ff87/swiftwood/Corvette/blower%20build/IMG_20110708_163006.jpg[/IMG]

Depends upon how lucky you are. I was very lucky, just took the mast nut off, when I had someone turn on the radio the mast started extending and I just pulled it the rest of the way up and out. The ribbon wasn't broken, just a few teeth stripped. Then just reverse the procedure to feed the new mast in after you take the sleeve off the old one and put it on the new one. Then put the nut back on and you are done. Mine took about 5 minutes.

If you ever have your console apart, it's real easy to put a switch in there to keep the antenna from going up when you are only playing cds/tapes.
Saves aome wear on the ribbon.

Tjerk- thanks for the well explained process.
Brian and Andy thanks for the input
Bill- Good idea for the putting a switch in - at some point. Will print this off and add it to my binder of ideas and procedures for the Vette.
Thanks All