Again, Package Cleaner does not unlock in Mint 8.
It works just fine for me, but I did fix that issue with the old version, so I'd bet my modified config file was left intact. Here's how to fix it:
In terminal: sudo gedit /usr/share/ubuntu-tweak/common/systeminfo.py
Find the follow information in the file, and add the Helena references as shown below.
return ['hardy', 'intrepid', 'jaunty', 'karmic', 'elyssa', 'Elyssa', 'felicia', 'Felicia', 'gloria', 'Gloria', 'helena', 'Helena']
return DistroInfo.codename in ['karmic', 'helena', 'Helena']