Pygame, Scoreboard issue

[etypaldo]

I am making a game using pygame and livewires. I am having trouble with the scoreboard- it updates appropriately but does not delete the old scoreboard, thus creating a blob of numbers:

class Ship(games.Sprite):
    """Ship, represents the player"""
    image = games.load_image("ship.bmp")
    DELAY = 25



    def __init__(self, x, y):
        super(Ship, self).__init__(image = Ship.image, x = x, y = y)
        self.missile_wait = 0


        self.score = games.Text(value = Missile.SCORE,
                        size = 30,
                        color = color.white,
                        top = 5,
                        right = games.screen.width - 10,
                        is_collideable = False)
        games.screen.add(self.score)




    def update(self):
        #move based on input
        if games.keyboard.is_pressed(games.K_LEFT):
            self.x -= 2
        if games.keyboard.is_pressed(games.K_RIGHT):
            self.x += 2
        #stops ship from moving off screen
        if self.x < 1:
            self.x = 1
        if self.x > games.screen.width:
            self.x = games.screen.width
        #update missile wait
        if self.missile_wait > 0:
            self.missile_wait -= 1
        #fire missile if space pressed and no delay
        if games.keyboard.is_pressed(games.K_SPACE) and self.missile_wait == 0:
            new_missile = Missile(self.x, self.top)
            games.screen.add(new_missile)
            self.missile_wait = Ship.DELAY
        #check for overlap, die accordingly
        if self.overlapping_sprites:
            for sprite in self.overlapping_sprites:
                sprite.die()
            self.die()

    def die(self):
        boom = Explosion(self.x, self.y)
        games.screen.add(boom)
        self.destroy()


        

class Missile(games.Sprite):
    """A missile from the player's ship"""
    image = games.load_image("missile.bmp")
    SCORE = 0

    
    def __init__(self, shipx, ship_top):
        super(Missile, self).__init__(image = Missile.image, x = shipx,
                                      y = ship_top - 25, dy = -2)



    def update(self):
        #if missile hits top of screen, destroys itself
        if self.top < 0:
            self.die()
        #if missile overlaps, destroy missile and overlapping sprites
        if self.overlapping_sprites:
            for sprite in self.overlapping_sprites:
                self.update_score()
                sprite.die()
            self.destroy()

    def die(self):
        self.destroy()

    def update_score(self):
        Ship.score.destroy()
        Missile.SCORE += 30
        self.score = games.Text(value = Missile.SCORE,
                        size = 30,
                        color = color.white,
                        top = 5,
                        right = games.screen.width - 10,
                        is_collideable = False)
        games.screen.add(self.score)

The ship is instantiated and creates an initial scoreboard. Every time a missile kills an enemy, it calls the 'update_score' method. The method attempts to delete the original scoreboard, but does not work. How do I get it to delete the scoreboard from another class?

[tbone2sk]

This code is taken from the aliens.py example from pygame.org.

http://www.pygame.org/docs/ref/examples.html#pygame.examples.aliens.main]

class Score(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.font = pygame.font.Font(None, 20)
        self.font.set_italic(1)
        self.color = Color('white')
        self.lastscore = -1
        self.update()
        self.rect = self.image.get_rect().move(10, 450)

    def update(self):
        if SCORE != self.lastscore:
            self.lastscore = SCORE
            msg = "Score: %d" % SCORE
            self.image = self.font.render(msg, 0, self.color)