>I take it that you company do not use these model 3599 cleaning machine?

Dave - True, we do not.  In the dim past I recall seeing cleaning machines
       for open reel tapes, with a supply of special razor blades for
scraping gunk off the oxide surface of the tape as it sped by.
Such external cleaning measures were certainly appropriate in those days,
where operators touched the surface of the media and the tape was very
much more open to the environment.

These days, all removeable media remains at least somewhat exposed to the
atmosphere, but contact through handling is virtually non-existent, and so the
need for such externalized cleaning is dubious.  The real value of a device such
as the Bow Industries "3599", in my experience, is in detecting and reporting
anomalies in the tape: wrinkles, creases, ripples, etc., which I have seen in
post mortems of failed cartridges.  It is valuable to determine such without
having to unreel the tape into a cardboard box, to be able to return such tapes
to the manufacturer with a report telling them that their manufacturing process
was stinko that day, letting defectively made tapes get out of the factory.

  Richard Sims, http://people.bu.edu/rbs/ADSM.QuickFacts