Get the text after ABCD in the word header!

Try:

Sub SearchHeader()
Dim i As Long, j As Long, StrPref As String
StrPref = "Procedure No. "
With ActiveDocument
  For i = 1 To .Sections.Count
    With .Sections(i)
      For j = 1 To 3
        With .Headers(j).Range
          With .Find
            .Text = StrPref & "[!^13]@^13"
            .Forward = True
            .MatchWildcards = True
            .Execute
          End With
          If .Find.Found = True Then
            MsgBox Mid(.Text, Len(StrPref) + 1, Len(.Text) - Len(StrPref) - 1)
          End If
        End With
      Next
    End With
  Next
End With
End Sub