you can do just the mast if the motor is functional.
1) turn the radio OFF
2) remove the nut and bezzel
3) have a buddy turn the radio ON wile you pull up on the antenna mast
4) observe the direction the teeth on the antena mast cable face
5) Spray some white lithium grease down the antenna hole
6) with the cable teeth facing the correct direction push the cable down into the antenna hole till it hits the bottom. ( it is not very far )
7) yell to your buddy to turn the radio OFF, as he / she does push and feed the antenna down into the hole, it will grab and walk its self in.
8) it might not go all the way down and that is fine, just put the bezzel and nut back on turn it on and let it fully cycle, turn it off and let it fully cycle. Twice should be enough.