Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1793/Kerr_MM4-V1.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-9506-Kerr_MM4-V1.ps) >>/Users/jc/w/tmp/Tune-9506-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1793/Kerr_MM4-V1.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_95060.log 286210 Log file, useful mostly for debugging
Tune-9506-Kerr_MM4-V1.abc 148 ABC music file with the extracted tune(s)
Tune-9506-Kerr_MM4-V1.ps 6 PostScript
Tune-9506-Kerr_MM4-V1.txt 148 Plain-text file with the extracted tune(s)
Tune-9506-get.log 4087 Log file, useful mostly for debugging
Tune-95067-24CountryDances_1800_Preston.abc 165 ABC music file with the extracted tune(s)
Tune-95067-24CountryDances_1800_Preston.pdf 2217 Portable Data Format
Tune-95067-24CountryDances_1800_Preston.ps 6 PostScript
Tune-95067-24CountryDances_1800_Preston.txt 165 Plain-text file with the extracted tune(s)
Tune-95067-get.log 5404 Log file, useful mostly for debugging
Tune-95069-get.log 3150 Log file, useful mostly for debugging
These files should be available for 24 hours.