pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-11469-20771_Jefferson_and_Liberty.ps) >>/Users/jc/w/tmp/Tune-11469-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/EliasHowe/MusiciansCompanionP2/20771_Jefferson_and_Liberty.abc

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 PNG]
filesizedescription
Tune-11469-20771_Jefferson_and_Liberty.abc 613 ABC music file with the extracted tune(s)
Tune-11469-20771_Jefferson_and_Liberty.ps 33829 PostScript
Tune-11469-20771_Jefferson_and_Liberty.txt 613 Plain-text file with the extracted tune(s)
Tune-11469-get.log 4910 Log file, useful mostly for debugging
These files should be available for 24 hours.