I have the same problem for Sony VGN-S460 heatsink fan problem

I trust that you have purchased the entire fan assembly as they are inseparable from the heatsink. You must disassemble the entire laptop in order to remove the fan assembly. they are two screws that are below the motherboard that must be remove in order for the fan assembly to come apart.
If you cannot achieve this yourself, or lack confidence in your ability to rebuild the unit after, you can send the unit to us at www.cowetacomputerstore.com and we will accomplish the desired outcome. We have worked on this system resolving this very issue.

farewell