harddrive replacement

I decided to replace the harddrive on my macbook. when I pulled the old hard drive out a piece of rubber (black - about 3" by .5") also came out. Now I can't put the new harddrive back in with the piece of rubber. I can insert the harddrive by itself - is it OK to do without the piece of rubber? What else can I do?

You are best of disassembling the thing if you feel brave and placing the drive and rubber back

Installing MacBook Core Duo Hard Drive Replacement

Without the 2 rubber guides the HD won't be properly supported. You'll need to remove the top case and refit with thin double sided tape.