link to migration assistant doesn't work. Where can I find it?

It's working fine here. Try restarting your Mac.

It's an application located in your Utilities folder.

Do you mean the link in the article to Apple Support Downloads? It works for me, now, and should take you here:

If not, try this one: http://support.apple.com/kb/DL1557

Sometimes an Apple server won't find the article you want immediately.