If you havnt fixed the probs yet try this.......
Before you rip the aerial apart, Try oiling the mast with WD40 when its fully extented, This will clean and lubricate it...
Regarding your speakers, Is your tweeter in the door ??
If so check the loom going into the door you may have broken or corroded pins. Or maybe someones messed about with somthing in the door and never connected them.
I think its the easiest and quickest thing to check before rou take the whole centre of your dash apart.. I have a feeling this is where your problem is........
Regards, P