[Ti] Noisy Fan Again

[Simon Royal]

Hi.

For the last few months I have been having some trouble with a noise  
fan on my TiBook. At first I thought it was the one on the right hand  
side (under the power button), but after closer inspection today it  
sounded like the middle one. There are three on this model, one under  
ear speaker grill and one directly in the middle at the back.

I took the bottom casing off a few weeks ago, blew out as much dust  
and rubbish as I could and it seemed to have solved it. However, the  
last few days the noise is back and worse than ever. It is a horrible  
dry grinding noise, but I still can't 100% tell where it is coming from.

Today I took the bottom off again, this time with the machine running,  
stood it on one end and then ran a number of heavy apps - iTunes,  
OpenOffice, Scribus, GIMP, Sequel 2 and MacTracker - at the same time  
to try and stress it out enough to get the fans on. Only the middle  
one came on and it was pretty quiet, just a normal fan noise. The  
other two didn't come on.

I put it all back together and within minutes the noise was back again  
- and is still doing it now. Listening carefully it sounds like it is  
the right hand side fan. I cannot feel any air coming out of the left  
or the back vent, but when I put my hand over the right vent the fan  
seems like it gets faster and the noise worsens.

I have checked and there is nothing stuck in it and no wires over it/ 
near it.

1. Is it dangerous, as in will it stop working?
2. Is it a known/common problem with the TiBooks?
3. Should replace it?
4. I cannot remember ever feeling the left hand side fan come on (no  
air coming out), would this put additional stress on the other two fans?
5. Can anyone with a Ti tell me if their left hand side fan comes on?
6. Can I spray it with WD40 or anything similar?
7. Is it the fan or is it just a noise vibration through some of the  
casing?
8. What would be needed for all the fans to come on?

I know I have probably asked this before, but I never got to the  
bottom of it. This TiBook is my only Mac and I do not want it to die.

Simon Royal
---
Site: http://www.simonroyal.co.uk. Twitter: http://twitter.com/SimonRoyal 
. Skype: Simon-Royal. (PowerBook G4 867Mhz, 1GB RAM, 80GB HD,  
SuperDrive, Mac OSX 10.5)