I know that the antenna isn't frozen cause normally I hear the motor grinding gears. But yesterday, there was no sound from the motor.

But this morning, when I got out, I saw that the antenna retracted in the night and it was working fine.

When I left work an hour ago, the antenna went up when I started my car, but didn't came down when I switched to CD with no sound from the antenna motor again.

But I was able to hear a little "click" coming from the antenna. I've played with it a bit and suddenly it went down. So I guess the motor is ok. It only seems to get stuck in the "up" position. When it's already retrated, it always come up with no problem.