To replace the thermal paste:
First, open up the laptop. There is no dedicated guide on this, so follow the first step of [guide|157704|this guide|new_window=true] to open your laptop. While you're at it, you might want to consider [guide|102668|creating a guide|new_window=true] for opening the laptop to help others. With the laptop open, remove the heatsinks from your CPU and, if present, the GPU. From there, follow [guide|744|this guide|new_window=true].
Good luck!