Hi Ed,  I had a roll client run into a similar problem with a local
postmaster in Iowa.  I was able to solve the problem by having my
client print out two sections from the following pages:

  DMM 173 Media Mail and Library Mail Prices and Eligibility for Retail

  DMM 173 Media Mail and Library Mail Prices and Eligibility for Retail
  173 Prices and Eligibility
    1.0 Media Mail and Library Mail Prices
    2.0 Basic Eligibility Standards for Media Mail and Library Mail
    3.0 General Content Standards
    View on pe.usps.com

Firstly, Section 4.1 Content Standards for Media Mail, Item e, and to
help with them understanding what a piano roll is --

  Player piano - Wikipedia, the free encyclopedia
  A player piano (also known as pianola) is a self-playing piano,
  containing a pneumatic or electro-mechanical mechanism that operates
  the piano action via pre-progra...
  View on en.wikipedia.org

Secondly, The first paragraph under Music Rolls.   This gave the
Postmaster the information he needed and never knew, and the problem
was solved.  I have even included a small single page with this
information included with rolls being sent to areas where packages
have been opened before.

Since the terrorists threats in our country have risen I have seen
a steep increase in the opening and delay of media mail packages.
Two parcels of a recent mailing that went through Chicago were held up
and inspected for several days.  When one of the packages arrived
the clients found the D-ring was missing from the roll.

Hope this information is of some help.

Kelly Goodman - Gnaw-Vol-ty Music Rolls
http://Gnaw-Vol-ty.com/