In the first run of TurboPrint Control Centre, the third step is: Help Browser.
I select firefox (the default) and click Test Help Browser. A Firefox window opens with the path file:///home/msquared/doc/html/4-1.html instead of file:///usr/share/turboprint/doc/html/4-1.html
Note that after the first run, the help browser (and the Test Help Browser button in Preferences) appear to work OK.