Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1748/Kohlers3.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-59791-Kohlers3.ps) >>/Users/jc/w/tmp/Tune-59791-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1748/Kohlers3.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Tune-59791-20302_Dunbars_Waltz-001.svg 24808 Scalable Vector Graphics format
Tune-59791-20302_Dunbars_Waltz.abc 865 ABC music file with the extracted tune(s)
Tune-59791-20302_Dunbars_Waltz.txt 865 Plain-text file with the extracted tune(s)
Tune-59791-Kohlers3.abc 145 ABC music file with the extracted tune(s)
Tune-59791-Kohlers3.ps 6 PostScript
Tune-59791-Kohlers3.txt 145 Plain-text file with the extracted tune(s)
Tune-59791-get.log 8515 Log file, useful mostly for debugging
These files should be available for 24 hours.