锐雯刀妹耐力测试h:sony vaio pcg-r505dl 笔记本如何升级内存？

大家好，我想换根256m的内存，但是要拆机器；在网上下载了说明书，是这样描述的：
1、 Turn off your notebook and disconnect all peripheral devices, such as your printer.
2、 Unplug the notebook and remove the battery packs.
3、 After the notebook has cooled, loosen and remove the two screws with the "<=" mark located on the bottom of your notebook. Use an appropriate screwdriver.
4、 Slide the LCD lock lever and lift the cover. Slide the keyboard toward the LCD display, then lift it away slightly.
5、 Lift the keyboard from the LCD display side, then gently turn it over on the touchpad space. Be careful not to detach the cable when lifting the keyboard.
6、 Touch a metal object (such as the connector panel on the back of your notebook) to discharge any static electricity.
7、 Slide the memory module out of the slot.
8、 Gently replace the keyboard, then press it into your notebook. Be careful not to detach the cable when lifting the keyboard.
9、 Close the notebook cover, then tighten the screws on the bottom of the computer.

上面第4步，要滑动LCD的什么开关，我找了半天找不到。请高手帮帮忙，谢谢了。。。