The only problem we encountered is the Red Secureline pen,
marked the cassettes, put them in and not one number showed up.
at end of run, what a mess!
I have noticed that some cassettes writing surface is different, not
all have the same roughness/surface, and the Secureline pens and
even pencils tend to "fade" out more on some brands than others, even with the
same array of examples you gave.
Also try to avoid touching the writing area, that had led to problems in the
past.
Gayle Callis