Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/Book08/CDfNH1783.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-8465-CDfNH1783.ps) >>/Users/jc/w/tmp/Tune-8465-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/Book08/CDfNH1783.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-8465-CDfNH1783.abc 148 ABC music file with the extracted tune(s)
Tune-8465-CDfNH1783.ps 6 PostScript
Tune-8465-CDfNH1783.txt 148 Plain-text file with the extracted tune(s)
Tune-8465-get.log 4053 Log file, useful mostly for debugging
Tune-84653-SocialDances2002.abc 152 ABC music file with the extracted tune(s)
Tune-84653-SocialDances2002.ps 6 PostScript
Tune-84653-SocialDances2002.txt 152 Plain-text file with the extracted tune(s)
Tune-84653-get.log 4234 Log file, useful mostly for debugging
Tune-84654-EliasHowe_MusiciansCompanionP2-1843-V1.abc 175 ABC music file with the extracted tune(s)
Tune-84654-EliasHowe_MusiciansCompanionP2-1843-V1.txt 175 Plain-text file with the extracted tune(s)
Tune-84654-get.log 3686 Log file, useful mostly for debugging
Tune-84659-get.log 5811 Log file, useful mostly for debugging
These files should be available for 24 hours.