It isn't a complex system. Take the antenna assembly out of the car for best access inside. You need to remove the chrome trim piece on top of the fender that holds the assembly in place along the top. There are two attaching bolts or nuts holding the bottom of the antenna assembly to the trunk floor. Disconnect the wiring and remove the antenna assembly from the car.
Remove the nut that holds the scroll cover (the black somewhat flat round part near the bottom of the antenna assembly). Pay attention to any washers. Carefully remove the scroll cover.
If there is anything wrong in here it could be the cause of your problem. Most common problem is part of the old antenna "tail" or "whip", the white plastic gear teeth strip is left behind and eventually gets in the way. You should be able to figure out where grease may be needed.
If the antenna whip gets loose while you have the scroll cover off (and it usually does), it is often easier to leave the mast off, reinstall the rest of the assembly, and feed the mast back in the same way as the instructions that came with the new mast.
I hope this helps.
