pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-6681-CR1-abc1.ps) >>/Users/jc/w/tmp/Tune-6681-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/Gow/CR1-abc1.abc

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Tune-6681-CR1-abc1.abc 98872 ABC music file with the extracted tune(s)
Tune-6681-CR1-abc1.ps 1013435 PostScript
Tune-6681-CR1-abc1.txt 98872 Plain-text file with the extracted tune(s)
Tune-6681-get.log 63111 Log file, useful mostly for debugging
Tune-66813-get.log 5573 Log file, useful mostly for debugging
These files should be available for 24 hours.