Figured this one out
VBA from button;
Private Sub Command0_Click()
DoCmd.RunSQL "DELETE MSC_load.* FROM MSC_load"
DoCmd.TransferText asImportFixed, "MSC_ddmmyy_ssss Import Specification", "MSC_Load", "C:\MSC.txt", False, ""
End Sub
Don't know what the [,""] does, but it fixed the problem