The Palatal is not substituted for the Guttural of the reduplicate of ku (kavate) in the intensive.,
As कोकूयते उष्ट्रः, कोकूयते खरः ॥ The कु here is कुङ् (Bhuadi 999), and not कु 'to make sound' (Adadi 33, कौति), nor कुङ् (Tudadi 108, कुवति) ॥ Of those two, we have चोकूयते ॥ Why do we say in the Intensive? Observe चुकुवे ॥,