Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1781/MSRPB.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-86745-MSRPB.ps) >>/Users/jc/w/tmp/Tune-86745-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1781/MSRPB.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-86745-13_Prince_George.abc 960 ABC music file with the extracted tune(s)
Tune-86745-13_Prince_George.ps 33669 PostScript
Tune-86745-13_Prince_George.txt 960 Plain-text file with the extracted tune(s)
Tune-86745-MSRPB.abc 142 ABC music file with the extracted tune(s)
Tune-86745-MSRPB.ps 6 PostScript
Tune-86745-MSRPB.txt 142 Plain-text file with the extracted tune(s)
Tune-86745-get.log 8619 Log file, useful mostly for debugging
These files should be available for 24 hours.