Handel's Messiah -- question about finding which ly file runs the whole shebang

[mrmoo]

Hi, I'm new to the list, but an old casual dabbler in Lilypond.

I have been tasked with coming up with some arranged brass parts for a quartet 
of 2 trumpets, trombone and tuba + organ for my church's Easter service.
I only need to do the Hallelujah chorus from Messiah, of course, and have 
already succeeded in finding which individual .ly files have the notes I need 
to change.

But before I do that, I thought I'd try a few dry runs on the source files as 
bundled on Mutopiaproject.org, and am already getting error messages just 
running the compile on the main.ly file.  They look like this:

\include 
         "Haendel/Oratorio/Messiah/common.ily"
/Volumes/Untitled/Program 
Files/Messiah-lys/Haendel/Oratorio/Messiah/main.ly:18:2: error: unknown escaped 
string: `\part'
  
  \part "Part I"
/Volumes/Untitled/Program 
Files/Messiah-lys/Haendel/Oratorio/Messiah/main.ly:18:2: error: syntax error, 
unexpected STRING

It also seems to be choking on each of the various occurrences of the strings 
\pieceTocTitle , \pieceToc , and \includeScore 

and so it continues for many lines.  I do finally get an output PDF, but it 
only contains "Messiah," "Table of Contents," "END OF THE FIRST PART" etc.

Is this a case of version mismatch?  All I can find so far is that the files 
were posted to Mutopia in December of 2009.

Thanks in advance for any light you can shed.
-Mark