I would go back to Dim rs as Object.
It sounds as if the findfirst is not finding a match, you could try this to test it
Set rs = Me.Recordset.Clone
rs.FindFirst "[NSN] = '" & Me![Combo36] & "'"
If Not rs.NoMatch Then
Me.Bookmark = rs.Bookmark
Else
Msgbox "No Match Found"
End If