Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/SCAJMR/ThomasMarsden.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-4186-ThomasMarsden.ps) >>/Users/jc/w/tmp/Tune-4186-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/SCAJMR/ThomasMarsden.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-4186-ThomasMarsden.abc 152 ABC music file with the extracted tune(s)
Tune-4186-ThomasMarsden.ps 6 PostScript
Tune-4186-ThomasMarsden.txt 152 Plain-text file with the extracted tune(s)
Tune-4186-get.log 4141 Log file, useful mostly for debugging
Tune-41860-get.log 7623 Log file, useful mostly for debugging
Tune-41861-get.log 5389 Log file, useful mostly for debugging
Tune-41863-get.log 4950 Log file, useful mostly for debugging
Tune-41865-get.log 4375 Log file, useful mostly for debugging
Tune-41867-get.log 3510 Log file, useful mostly for debugging
Tune-41868-get.log 4284 Log file, useful mostly for debugging
Tune-41869-get.log 4598 Log file, useful mostly for debugging
These files should be available for 24 hours.