\font\ninett=cmtt9

\def\editorsnote{\noindent Editor's Note: The present variant of
  this {\ninett C/WEB} source file has been modified for use in
  the \TeX~Live system.}

\def\changedsections{\jobname.chs}
\def\readchanges{\input \changedsections}
\newread\testread \newwrite\writechanges
\openin\testread=\changedsections\relax
\ifeof\testread % First run
  \let\readchanges=\relax
  \let\CH=\ch
  \def\ch#1.{\begingroup
    \let\\=\BS \let\*=\let \let\ch=\relax
    \immediate\openout\writechanges=\changedsections
    \immediate\write\writechanges{\par\noindent\ch#1.}
    \immediate\closeout\writechanges
    \let\ch=\CH \ch#1.
    \endgroup}
\else\closein\testread % Second run
\fi