Here is the new code with John Wilson's find
Code:
Sub ChangeLineColor()
Dim sld As Slide, shp As Shape, GrayColor(1 To 3) As Long, Arr As Byte
Dim CheckColor As Long
'Set GrayColors
GrayColor(1) = 10921638
GrayColor(2) = 12287562
GrayColor(3) = 12566463
For Each sld In ActivePresentation.Slides
sld.Select 'not necessary but fun to watch
Debug.Print sld.SlideIndex 'again not necessary but useful if errors
For Each shp In sld.Shapes
If shp.Type <> msoGroup Then
shp.Select 'not necessary but fun to watch
CheckColor = shp.Line.ForeColor.RGB
For Arr = 1 To 3
If GrayColor(Arr) = CheckColor Then
shp.Line.ForeColor.RGB = 12287562 'Change to blue
End If
Next Arr
End If
Next shp
Next sld
MsgBox "done"
End Sub