Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/JamesOswald/CPC/21411_Oswalds_Dream.abc/all"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-4201-all.ps) >>/Users/jc/w/tmp/Tune-4201-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/JamesOswald/CPC/21411_Oswalds_Dream.abc/all

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Coll_42010.log 447209 Log file, useful mostly for debugging
Coll_42012.log 458410 Log file, useful mostly for debugging
Coll_42014.log 909817 Log file, useful mostly for debugging
Form_42011.log 959 Log file, useful mostly for debugging
Tune-4201-all.abc 171 ABC music file with the extracted tune(s)
Tune-4201-all.ps 6 PostScript
Tune-4201-all.txt 171 Plain-text file with the extracted tune(s)
Tune-4201-get.log 4055 Log file, useful mostly for debugging
Tune-42018-get.log 4693 Log file, useful mostly for debugging
These files should be available for 24 hours.