Texas300

Hi Folks:

My GS 300 just started making a funky and annoying noise from under the dash. I had to pull the glove compartment anyway because I was putting in a GROM audio unit. I did some searching on this forum regarding the noise and found this thread that makes me think the AC slide guide is getting hung up or the servo is going out.

Here is a YouTube of the noise (please excuse my two year old yelling "beep beep" in the background):
So here are my questions:

1. What kind of grease should I be using on the slide guide?
2. Is there a way to tell ahead of time if the servo needs to be replaced?
3. If I grease it, how much grease should I put on it? I know in situations like that many people put too much grease/thermal compound/whatever on what they're doing, and consequently I have a habit of putting too little. How do I know how much is correct?
4. Is there a guide somewhere on this? I tried searching but came up with a lot of results and didn't find one that matched what I was looking for. I'm sure its there but I'm not finding it. Or maybe this is just really simple and I'm over thinking the whole thing.

Thanks for helping the n00b.