How can I tell which vmax I have? According to the service manual there are 3 supplementary manuals, each apply to a different VMX12 prefix. Example VMX12H, VMX12HC, VMX12N, VMX12E, VMX12U, VMX12S. I realize that my serial # should match sertain digets, which would tell me which model I had. No such luck, my serial # doesn't match any digets in my service manual.