Hope you managed to resolve your issue, I am a Logic 9 user with similar circumstances, moved hard drive by cloning and found the missing plugins. Difference with my situation is that the Plugins were third party and the native plugins were preserverd.
So in your instance your native plugins may be effected by a permissions, worth checking. So you could open Disk Utility > repair permissions on the Macintosh HD boot disk.
If not I have also read trashing the AudioUnits cache. It is here: /Users/'you'/Library/Caches
Then doing Audion Units rescan can help repair issues.
Choose Logic > Preference > Audio Units manager > rescan.