It sounds like the white toothed strip is still intact. You will be able to remove the broken mast and its still-functional plastic strip, without having to touch the motor under the fender. Much simpler for you to DIY than the guys who have to take apart the motor to retrieve the broken plastic strip.
Dont' be discouraged by this long post......It's a one-sip-of-beer job.
Find a friend (not necessary, but helpful. It's DIY if you roll down the passenger window and have long arms and are quick footed.)
Unscrew the slotted collar nut that holds down the base of the antenna mast at your right front fender. You can turn it with a large pliers if you don't have other tools. Carefull not to scratch the chrome on the nut, or the paint on your fender. You do not remove the rubber boot. Just leave it there.
Turn on radio. Antenna and toothed strip comes up and will stop at some poinit. My 2000 TLC has an up/down antenna button on the dash. Give the up button an extra poke to be sure it's all the way up. Notice which direction the teeth are facing. The Factory Service Manual says they should face rearward. Do NOT turn off the radio.
Now pull straight up on the plastic toothed strip to pop it out of the motor. A gentle 2-10lbs of upward force should do it. The tip of an intact strip will still have a bevelled cut at the end to make it slightly pointy. (The end of a broken strip with be more obviously cracked straight across; which would indicate there might be a need to dive into the motor. ) Throw away the old antenna mast/strip.
(I don't remember if the rubber gromet boot is permanently mounted to the antenna mast or not. If it comes out with the old mast, and if you can see a new boot on the new mast, then it should be obvious as to whether you need to reuse the old rubber boot.)
Insert the end of the new white plastic toothed strip, with teeth facing rearward. Feed the strip down into the hole until you feel it go into the motor. When the first tooth hits the motor, push down a little to make sure it is engaged with the gear that will wind it in when you turn off the radio. Make sure the mast is in its shortest position and the entire plastic strip is exposed, ready to get drawn into the motor.
Now, tell your helper to turn OFF the radio. The motor will start winding in the toothed strip while you carefully keep feeding it into the hole. Your challenge is to feed it in with the teeth pointed the same way the whole time, without twisting. It goes slowly enough that you will be able to keep up. When it gets near the end, you can guide the antenna mast down into the hole. When the motor stops winding, don't worry if there's still some plastic toothed strip showing. Insert the mast into the hole (extend the antenna with your hand a little bit to take up the slack of the plastic strip that's still showing).
Put the collar nut back on to secure the mast onto the base in the fender, and tighten down (doesn't need too much torque).
Now turn the radio back ON. The antenna will come up and stop.
Now turn the radio OFF. The antenna should go ALL THE WAY down this time, taking up the extra slack.
Finish your beer.
