Got HTTP status 404 Not Found for "http://roaringjelly.org/~jc/music/book/JamesOswald/CPC/20731_Johnny_Cope.abc/all"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-29952-all.ps) >>/Users/jc/w/tmp/Tune-29952-get.log 2>&1" returned status 256
http://roaringjelly.org/~jc/music/book/JamesOswald/CPC/20731_Johnny_Cope.abc/all

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Form_29952.log 986 Log file, useful mostly for debugging
Tune-29952-all.abc 169 ABC music file with the extracted tune(s)
Tune-29952-all.ps 6 PostScript
Tune-29952-all.txt 169 Plain-text file with the extracted tune(s)
Tune-29952-get.log 9240 Log file, useful mostly for debugging
These files should be available for 24 hours.