Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/session/PF/Belmont/Loch_Lomond-G-32-6w.abc/song"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-87596-song.ps) >>/Users/jc/w/tmp/Tune-87596-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/session/PF/Belmont/Loch_Lomond-G-32-6w.abc/song

Error exit status 256; here are some files to check:

[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Tune-87596-get.log 4083 Log file, useful mostly for debugging
Tune-87596-song.abc 170 ABC music file with the extracted tune(s)
Tune-87596-song.ps 6 PostScript
Tune-87596-song.txt 170 Plain-text file with the extracted tune(s)
These files should be available for 24 hours.