Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/CNS/Tune-74657-tmp.abc/tmp"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-9726-tmp.ps) >>/Users/jc/w/tmp/Tune-9726-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/CNS/Tune-74657-tmp.abc/tmp

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Coll_9726.log 474312 Log file, useful mostly for debugging
Coll_97261.log 468770 Log file, useful mostly for debugging
Coll_97265.log 3307098 Log file, useful mostly for debugging
Coll_97266.log 466002 Log file, useful mostly for debugging
Tune-9726-get.log 20461 Log file, useful mostly for debugging
Tune-9726-tmp.abc 154 ABC music file with the extracted tune(s)
Tune-9726-tmp.ps 6 PostScript
Tune-9726-tmp.txt 154 Plain-text file with the extracted tune(s)
Tune-97260-get.log 4487 Log file, useful mostly for debugging
Tune-97261-get.log 5390 Log file, useful mostly for debugging
Tune-97265-SallysFancy.abc 381 ABC music file with the extracted tune(s)
Tune-97265-SallysFancy.ps 6 PostScript
Tune-97265-SallysFancy.txt 381 Plain-text file with the extracted tune(s)
Tune-97265-get.log 12839 Log file, useful mostly for debugging
Tune-97267-get.log 8508 Log file, useful mostly for debugging
Tune-97268-get.log 4225 Log file, useful mostly for debugging
These files should be available for 24 hours.