Is there a miscount in Barks' echo story (WDC 105)?

[Daniel van Eijmeren]

I don't know if this subject has been brought up before, but I have a 
question about Barks' paid echo's story (WDC 105). It seems to me that 
there's a miscount of the echo's and the total deposit. 

Am I right about that, or am I making a miscount myself? See my summary 
below. The line of dots (".......") means that no payment is shown.
The quotes refer to the sounds that are echoed by the nephews.

- - - - - - -

The nephews need 60 cents to go to the ball game. 
They decide to earn them by making echo's in Thrushwhistle Glenn.
The deposit is 10 cents for an echo.

  panel 2.3 - 10 cent ("Oh lay-eee Oh lay-ee Ooooooooo")
  panel 2.8 - 10 cent ("Huey, Dewey, and Louie are PANTYWAISTS!")
  panel 3.1 - 10 cent ("Dewey's got a GIRL!")
  panel 3.7 - ....... ("Fweeeng! Fwanng! Fwoing!) 
  panel 4.5 - ....... ("Screeowl Yeeorr")
  panel 5.4 - 10 cent ("Gkkkkqzffjgmmmssfxxxwllvkkkski! Gckfpt!")

Subtotal: 6 different echo's.

However, in panel 6.2, one nephew says that he watched Donald put 
*5* dimes in their coin box.

  panel 6.5 - 10 cent ("Feetle Tee Feetle Tetee Tetwee!")
  panel 6.8 - ....... ("Moo! Squawk! Grind! Whonk!)

Subtotal: 2 different echo's.

The sound in panel 7.5 doesn't count, because it gets no echo.

In panel 8.4, one nephew says: "If I'm not mistaken, Unca' Donald put 
SEVENTY cents in there!" (This is 10 cents more than they need, so one 
other nephew concludes they'll have enough for popcorn, too.)

Total: 8 different echo's, 1 unanswered sound, 
7 payments according to the story.

- - - - - - -

If the nephew in panel 6.2 is right about the five dimes, then the total 
sum of payments is right. (5 + 2 = 7) But if so, then the nephews must 
have done one echo for free. Either the one from panel 3.7 (jews-harp), 
or the one from panel 4.5 (musical saw). For these two, no payment is 
shown.

Why would the nephews do one echo for free? The story gives no reasons 
or explanations, at least not to me. Rather the contrary, because the 
story plot shows that the nephews make a point of being paid for each 
echo. (They ignore the unpaid sound in panel 7.5.)

So, this is why I tend to think that there's a miscount in this story.

What do you think? And you? And you? And you? And you?

--- Daniël
--- Daniël
--- Daniël
--- Daniël