Just looked and my 2013 ST actually has one serial number tag that I could find and it's on the front of the headset and numbers are also worn off from the cables rubbing on it, just like yours. The other 2 white labels that I thought were vin # labels turned out to be Emission Stickers. It could be stamped somewhere, but I didn't see it. I don't want to post my vin here, but I'll pm you after dinner with the 2 numbers that you are missing from mine from the bill of sale I have. . I have no idea though whether they are appropriate for yours, but they'll at least be numbers Tomos uses.