Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/cache/Tune-8513-jig.abc/tmp"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-5626-tmp.ps) >>/Users/jc/w/tmp/Tune-5626-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/cache/Tune-8513-jig.abc/tmp

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Coll_56260.log 462609 Log file, useful mostly for debugging
Coll_56261.log 473809 Log file, useful mostly for debugging
Coll_56262.log 472412 Log file, useful mostly for debugging
Coll_56266.log 827731 Log file, useful mostly for debugging
Form_56260.log 1816 Log file, useful mostly for debugging
Form_56262.log 1117 Log file, useful mostly for debugging
Form_56269.log 1044 Log file, useful mostly for debugging
Tune-5626-get.log 3963 Log file, useful mostly for debugging
Tune-5626-tmp.abc 155 ABC music file with the extracted tune(s)
Tune-5626-tmp.ps 6 PostScript
Tune-5626-tmp.txt 155 Plain-text file with the extracted tune(s)
Tune-56260-get.log 191911 Log file, useful mostly for debugging
Tune-56261-get.log 25478 Log file, useful mostly for debugging
Tune-56263-get.log 5697 Log file, useful mostly for debugging
Tune-56266-get.log 3073 Log file, useful mostly for debugging
Tune-56267-get.log 4740 Log file, useful mostly for debugging
These files should be available for 24 hours.