Can't get fan off my CPU

I have an Asus P4B Motherboard and am trying to remove my CPU so I can install an upgraded one. Problem is, I can't seem to get the fan off of the heat sink. It seems loose and wiggles around, but something is catching it and it won't lift out.

I've also posted this question on the Asus forums but no answer yet. Are there any techies on this site that may help me out?

J.R.

Is this your homebuilt computer?

A friend did it for me.
Can't locate him now.

J.R.

You don't need to remove the fan from the heatsink, it comes off as one piece. There should be two little levers, on the top, flip them up and make sure that the 4 corner clips are loose, it should then lift off. If you still have problems, you can get the manual with pictures from the Asus website.

Ah, wait a minute the fan doesn't come of the heatsink, you have to remove the complete assembly