Got HTTP status 404 Not Found for "http://roaringjelly.org/~jc/music/book/GM/Worse_for_Better.abc/1750"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-53175-1750.ps) >>/Users/jc/w/tmp/Tune-53175-get.log 2>&1" returned status 256
http://roaringjelly.org/~jc/music/book/GM/Worse_for_Better.abc/1750

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.65 512x512 PNG]
filesizedescription
Tune-53175-1750.abc 156 ABC music file with the extracted tune(s)
Tune-53175-1750.ps 6 PostScript
Tune-53175-1750.txt 156 Plain-text file with the extracted tune(s)
Tune-53175-1770.abc 8253 ABC music file with the extracted tune(s)
Tune-53175-1770.pdf 160199 Portable Data Format
Tune-53175-1770.ps 103870 PostScript
Tune-53175-1770.txt 8253 Plain-text file with the extracted tune(s)
Tune-53175-get.log 20760 Log file, useful mostly for debugging
These files should be available for 24 hours.