Normally with the HD enclosure there come a set of screws. use these to screw down the HD in the enclosure since you need to flip it up side down to reinstall it into the MBP
Step 8: The cable needs quite a hard pull to come out, be careful to pull straight! When reconnecting I used 2 wooden sate stick to push the connector back in.
Now running an sad for startup and the old HD as capacity storage. Thanks for the great manual on how to do these!