BB: The Pali terms for parts of the lute (vina) are camma, doni danda, upavina, tanti, kona. The simile occurs at Milinda's Questions 5, inclusive of the list of terms (preceded by patta, sling).
"The King would split the lute into ten or a hundred pieces ... Then he would say: 'A poor thing, indeed sir, is this so-called lute, as well as anything else called a lute. How the multitude are utterly heedless about it, utterly taken in by it!"
BB: The meaning is obscure. Spk paraphrasess: "It is not only the lute that is a poor thing, but like this so-called lute, whatever else is bound with strings---all that is just a poor thing."
So, too, bhikkhus, a bhikkhu investigates form to the extent that there is a range for form, feeling... perception... volitional formations... conciousness... As he investigates ... whatever notions of 'I' or 'mine' or 'I am' had occurred to him before no longer occur to him."
Spk: The five aggregates are like the lute, the meditator is like the king. As the king did not find any sound in the lute even after splitting it up and searching, and therefore lost interest in the lute, so the meditator, exploring the five aggregates, does not see any graspable "I" or "mind" and therefore loses interest in the aggregates. By the term "I" or "mine" or "I am" in regard to form, etc, the three "grips" of views, craving, and conciet are respectively described. These do not exist in the Arahant.
BB: There is an important difference between the king that the meditator, not conveyed either by sutta or commentary: In the parable the king, looking for the sound of the lute by taking the instrument apart, seems foolish, while the meditator, dissecting the aggregates to dispel the delusion of a self, becomes wise.
Spk ends the commentary of the sutta with a quotation from the Great Commentary (no longer extant):
"In the beginning virtue is discussed,
In the middle, development of concentration,
And at the end, Nibbana:
The Simile of the Lute is thus composed."