Can't see old time machine backups I've installed a new HDD in my iMac, so i reinstalled OS X. I used migration assistant to set back only the settings. I also wanted to set back some other folders, but since my new HDD was smaller than the original one I wanted to dive in this later on.

Now I have setup time machine for my new installation of OS X (with the same computer name). Frankly I can't access the files/folders of the old backup anymore. In time machine the dates of the backups show up, but I can't move to them. Also migration assistant only shows the new backups and not the old ones anymore. I think the old backups are still there, since the time machine backup file is around 500 GB and the backups from the new installation are around 40 GB.

Is there a way I can get to the old backups?
Time machine can be problematic. A couple of things to try: 


open a folders that you can't access in finder, right click > get info, and check permissions. Does your user have read &amp; write permission?  
make sure your new HD disk name is the same as the old one.
try to access through time machine or finder.  
give it time - there are references in the apple forums of backups not being browsable right away, but eventually becoming available.