Zoom = City Music
If its some "regular" hardware problem like jack sockets and switches I'm sure the usual bunch here eg Randolf, Blueark and Gsonique(Guys I'm just assuming that you do repairs!) can help you out.
If its some deep internal Zoom digital processor chip yadda yadda... better luck in ahem... City Music.
I'd say contact the guys about. And before you ask how, don't be lazy. Search the forum and PM them. Good luck! It sure sucks buying something and not working!