The automatic antenna is operated by a motor, connected to a drum which has a toothed belt (in your model's case), which in turn is attached to the antenna mast. Pulling on the mast will likely damage the connection, or the belt, or both. The only recourse is to remove the drum and motor and open the case.
First you have to disconnect the antenna from the rear of the radio. This requires removal of the center console. Once you unplug the antenna cable, tie a 12' string to it and pull it through the firewall, behind the glovebox (I used kitchen twine, hundreds of uses). I had to remove the glovebox to do this. The string is useful for reinstalling the cable. Don't pull it all the way through; ideally one end should be on the engine bay side of the firewall and the other should be near the rear of the radio.
Remove the bezel (nut) on the fender. Tape your fender first, then when the tool slips off the nut, you'll likely do less damage to your paint. The best tool for this nut is a bicycle tool designed to remove the nut which holds the crank arm on the frame (your local bike shop has one, or two).
I take my truck to the bike shop and borrow theirs, I have no other use for it. You can do it with a screwdriver and hammer, unless it's really tight, in which case you'll scratch your fender and ruin the nut.
Next, disconnect the power cable form the antenna. It's near the inner fender access hole for the antenna. Unbolt the unit and pull it out.
Do not disconnect the motor from the case, you'll lose the brushes that way. (Ask me how I know)
You should be able to operate the mast with the dash switch, while someone holds the unit after you remove it from the outer fender. This way you can troubleshoot your repair before reinstalling the mast.
This is a one banana job, but it will take some time. If you've removed the dash and near panels before, allow half an hour. If not, allow 2 hours (you will clean all that stuff under the trim panels, and wash them, won't you?)
HTH