Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/1748/RSCDS_Graded1.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-9297-RSCDS_Graded1.ps) >>/Users/jc/w/tmp/Tune-9297-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/1748/RSCDS_Graded1.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_92979.log 371440 Log file, useful mostly for debugging
Tune-9297-RSCDS_Graded1.abc 150 ABC music file with the extracted tune(s)
Tune-9297-RSCDS_Graded1.ps 6 PostScript
Tune-9297-RSCDS_Graded1.txt 150 Plain-text file with the extracted tune(s)
Tune-9297-get.log 4127 Log file, useful mostly for debugging
Tune-92974-get.log 13887 Log file, useful mostly for debugging
Tune-92979-SCD_Book49-V2.abc 150 ABC music file with the extracted tune(s)
Tune-92979-SCD_Book49-V2.ps 6 PostScript
Tune-92979-SCD_Book49-V2.txt 150 Plain-text file with the extracted tune(s)
Tune-92979-get.log 4179 Log file, useful mostly for debugging
These files should be available for 24 hours.