Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/Entry/Gow-CR-abc1.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-5750-Gow-CR-abc1.ps) >>/Users/jc/w/tmp/Tune-5750-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/Entry/Gow-CR-abc1.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_57502.log 138880 Log file, useful mostly for debugging
Coll_57507.log 940641 Log file, useful mostly for debugging
Tune-5750-Gow-CR-abc1.abc 149 ABC music file with the extracted tune(s)
Tune-5750-Gow-CR-abc1.ps 6 PostScript
Tune-5750-Gow-CR-abc1.txt 149 Plain-text file with the extracted tune(s)
Tune-5750-get.log 4093 Log file, useful mostly for debugging
Tune-57506-24CountryDances_1810_Button_Whitaker.abc 173 ABC music file with the extracted tune(s)
Tune-57506-24CountryDances_1810_Button_Whitaker.pdf 2217 Portable Data Format
Tune-57506-24CountryDances_1810_Button_Whitaker.ps 6 PostScript
Tune-57506-24CountryDances_1810_Button_Whitaker.txt 173 Plain-text file with the extracted tune(s)
Tune-57506-get.log 5634 Log file, useful mostly for debugging
Tune-57508-ThomasMarsden.abc 149 ABC music file with the extracted tune(s)
Tune-57508-ThomasMarsden.pdf 2217 Portable Data Format
Tune-57508-ThomasMarsden.ps 6 PostScript
Tune-57508-ThomasMarsden.txt 149 Plain-text file with the extracted tune(s)
Tune-57508-get.log 4963 Log file, useful mostly for debugging
These files should be available for 24 hours.