Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1759/Urbani_Liston_1800.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-4168-Urbani_Liston_1800.ps) >>/Users/jc/w/tmp/Tune-4168-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1759/Urbani_Liston_1800.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Coll_41682.log 658061 Log file, useful mostly for debugging
Tune-4168-Urbani_Liston_1800.abc 155 ABC music file with the extracted tune(s)
Tune-4168-Urbani_Liston_1800.ps 6 PostScript
Tune-4168-Urbani_Liston_1800.txt 155 Plain-text file with the extracted tune(s)
Tune-4168-get.log 4230 Log file, useful mostly for debugging
Tune-41681-10891_.abc 50 ABC music file with the extracted tune(s)
Tune-41681-10891_.ps 6 PostScript
Tune-41681-10891_.txt 50 Plain-text file with the extracted tune(s)
Tune-41681-get.log 3842 Log file, useful mostly for debugging
These files should be available for 24 hours.