Option Explicit
Public WithEvents PieceFail1 As MSForms.CheckBox

Private Sub PieceFail1_click()
    Select Case PieceFail1.Name
        Case "CheckBox1"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label1").Caption).Value = "ChartV_Fail"
        Case "CheckBox2"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label2").Caption).Value = "ChartV_Fail"
        Case "CheckBox3"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label3").Caption).Value = "ChartV_Fail"
        Case "CheckBox4"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label4").Caption).Value = "ChartV_Fail"
        Case "CheckBox5"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label5").Caption).Value = "ChartV_Fail"
        Case "CheckBox6"
                Sheets("Base").Range("AU" & Piece_Group1.Controls("Label6").Caption).Value = "ChartV_Fail"
    End Select
End Sub