Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/CDM6/MoF.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-3975-MoF.ps) >>/Users/jc/w/tmp/Tune-3975-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/CDM6/MoF.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-3975-MoF.abc 140 ABC music file with the extracted tune(s)
Tune-3975-MoF.ps 6 PostScript
Tune-3975-MoF.txt 140 Plain-text file with the extracted tune(s)
Tune-3975-get.log 8107 Log file, useful mostly for debugging
Tune-90677-Tune-3975-10381_Duet_Marchia.abc 180 ABC music file with the extracted tune(s)
Tune-90677-Tune-3975-10381_Duet_Marchia.pdf 2217 Portable Data Format
Tune-90677-Tune-3975-10381_Duet_Marchia.ps 6 PostScript
Tune-90677-Tune-3975-10381_Duet_Marchia.txt 180 Plain-text file with the extracted tune(s)
These files should be available for 24 hours.