I just picked up an old M500. Does anybody know Where the serial number is located? The dealer says they can't help me until I give them the number. Of course my machine is older than anyone working there. LOL I found a metal plate with a five digit number and the 500(model number) stamped into it. The writing was all worn off so I couldn't be sure sure if that was it or not. I gave that number to the guy working the counter and he looked at me like I was crazy. Thanks......dan "Joe"