Sub Articulo 105.0

 I'm working on my thesis, using the report class in LaTeX2e.  I want to
 have running headers with the chapter and section titles, so I'm using
 the "twoside" option and \pagestyle{headings}.
 
 The problem is, I've got some sections with very long titles which
 overrun the page margins in the headers.  I've tried substituting a
 shorter section title in the header using \markright, e.g.
 
         \section{Long section title causing header to overrun margins}
         \markright{\uppercase{\thesection\ short title}}
 
 This works...sort of.  The original, long title is used on the page
 containing the section command, while the short title is used on
 subsequent pages.
 
 I'm guessing that \markright allows one to manipulate the heading, but
 only if no marking commands have been called yet for the current page.
 How can I overcome this restriction?
 
 BTW, I have looked at the relevant sections in the LaTeX Companion, but
 am generally more confused for doing so.  I have looked a bit at the
 fancyheadings package, but I'm not sure that it will solve the problem.