here is the specific quote:
www.bitsavers.org/pdf/dec/disc/RM05_Handbook.pdf
pages 2-43 and 2-44
" CDC does not recommend head or media cleaning on the 9766. <- same heads as
RM03/9762
The tolerances involved are much more critital than the
RP06 or similar drives.
Due to the 'Burnished media' technology used on these packs,
the normal pack cleaning procedures tend to leave a residue
on the platter surfaces. The media requires a special power
wash cycle to insure that all the residue is removed. Again,
only a keen eye trained to recognize a media defect can spot
a problem inspecting a pack. CDC recommends a program of
media inspection at certain intervals but will not recommend
any cleaning. Therefore a clean environment and proper
storage of media to prevent pack contamination is strongly
suggested.
"