Common causes for intermittent antenna???
 

The antenna seems to work perfectly half of the time. Otherwise it doesn't come up at all but I can hear a slight "click" coming from the antenna motor, just no movement. Pressing the switch a dozen times or so will get it to come up though.

Dirt is the top cause of all antenna woes.

I clean masts with rubbing alcohol, and lube them with silicone grease.
You can also use white lithium grease, or any of the various 'dry-film' lubricants. There are even these special-purpose mast lubricants pads that come in little packets. I think these are not worth the money, but some people swear by them, and they do work. In road salt areas, this will need to be done regularly to keep things working well.

Start there, and see if it helps.