From what I understand, there were just some parts that there were not any made extra of. After talking with Mike, they get their extra parts from breaking down built-up, ready-to-sell units... This means that depending on how far they break down the shell, there might not be any parts.
For example, try finding the MU stands on the front/rear deck of the RS-11s, or the single note horns from the sides, that definately break off...
We feel your pain, Rich.
Thanks,
Mario