Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/reel/Gow-CR-abc2.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-4870-Gow-CR-abc2.ps) >>/Users/jc/w/tmp/Tune-4870-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/reel/Gow-CR-abc2.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_48706.log 284812 Log file, useful mostly for debugging
Tune-4870-Gow-CR-abc2.abc 148 ABC music file with the extracted tune(s)
Tune-4870-Gow-CR-abc2.ps 6 PostScript
Tune-4870-Gow-CR-abc2.txt 148 Plain-text file with the extracted tune(s)
Tune-4870-get.log 4089 Log file, useful mostly for debugging
Tune-48701-10123_Morpeths_March.abc 580 ABC music file with the extracted tune(s)
Tune-48701-10123_Morpeths_March.pdf 10441 Portable Data Format
Tune-48701-10123_Morpeths_March.ps 33123 PostScript
Tune-48701-10123_Morpeths_March.txt 580 Plain-text file with the extracted tune(s)
Tune-48701-get.log 7323 Log file, useful mostly for debugging
These files should be available for 24 hours.