Got HTTP status 404 Not Found for "http://roaringjelly.org/~jc/music/book/GM/proto.abc/1750"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-73103-1750.ps) >>/Users/jc/w/tmp/Tune-73103-get.log 2>&1" returned status 256
http://roaringjelly.org/~jc/music/book/GM/proto.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-73103-1750.abc 145 ABC music file with the extracted tune(s)
Tune-73103-1750.ps 6 PostScript
Tune-73103-1750.txt 145 Plain-text file with the extracted tune(s)
Tune-73103-get.log 3937 Log file, useful mostly for debugging
These files should be available for 24 hours.