There is an error in the file /etc/apt/apt.conf.d/00knoppix in declaring the stable package. Discussed in post: Flash Player no longer Directly Supports Linux .
...the second line sets ... default release ...Wheezy in Knoppix 7.2.0 ... prevents a sizeable number of packages from being marked as upgradable ... Before commenting out this line ...
The default apt line needs to be hashed. I will now try the next step: changing my nvidia drivers...