Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/CentColl/RSCDS_Graded1.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-6755-RSCDS_Graded1.ps) >>/Users/jc/w/tmp/Tune-6755-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/CentColl/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_67552.log 714263 Log file, useful mostly for debugging
Coll_67553.log 288546 Log file, useful mostly for debugging
Coll_67557.log 1288130 Log file, useful mostly for debugging
Tune-6755-RSCDS_Graded1.abc 154 ABC music file with the extracted tune(s)
Tune-6755-RSCDS_Graded1.ps 6 PostScript
Tune-6755-RSCDS_Graded1.txt 154 Plain-text file with the extracted tune(s)
Tune-6755-get.log 9508 Log file, useful mostly for debugging
Tune-67554-Gow-CSR2-abc2.abc 151 ABC music file with the extracted tune(s)
Tune-67554-Gow-CSR2-abc2.pdf 2217 Portable Data Format
Tune-67554-Gow-CSR2-abc2.ps 6 PostScript
Tune-67554-Gow-CSR2-abc2.txt 151 Plain-text file with the extracted tune(s)
Tune-67554-get.log 4977 Log file, useful mostly for debugging
These files should be available for 24 hours.