droid x back hard key broke. what part do i buy?

[naomiljohnson]

I bought a used Droid x on ebay and when I got it the back hard key is broke. Do I need to buy a new flex cable to fix it? I don't have a problem fixing it but I can't fuigure out what part to buy. I already ordered a new lcd due to having a few shadows on it. Please help. My phone is not rooted so I can't get any aps. For soft keys. Thanks for the help.