Bad batch of cards, or reader/writer issue?

[teenix]

A quick test could be writing the cards with the 65 and see how they hold up. If they fail, and you know the 65 writes cards ok, then the cards could be faulty.

If the cards stay readable, then the 97 may have problems, which could be lots of things. Aged capacitors, poor contact from the ribbon cable, failing sense or CRC chip, corrosion, dirty RW head etc

cheers

Tony