Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/sets/GentlemansMagazine.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-96675-GentlemansMagazine.ps) >>/Users/jc/w/tmp/Tune-96675-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/sets/GentlemansMagazine.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-96675-GentlemansMagazine.abc 155 ABC music file with the extracted tune(s)
Tune-96675-GentlemansMagazine.ps 6 PostScript
Tune-96675-GentlemansMagazine.txt 155 Plain-text file with the extracted tune(s)
Tune-96675-NewCenturyHornpipe.abc 436 ABC music file with the extracted tune(s)
Tune-96675-NewCenturyHornpipe.gif 0 Graphics Interchange Format, the proprietary scan-line picture format
Tune-96675-NewCenturyHornpipe.ps 36631 PostScript
Tune-96675-NewCenturyHornpipe.txt 436 Plain-text file with the extracted tune(s)
Tune-96675-get.log 15185 Log file, useful mostly for debugging
These files should be available for 24 hours.