Can you provide a summary of the main qualities of a Sadguru as presented in Chapter 48?

Certainly. Chapter 48 of the Sai Satcharitra defines a Sadguru not by external knowledge but by internal realization. The key qualities mentioned are: possessing direct, full self-experience, which they can impart to others; being completely free from ego and not viewing themselves as superior to their disciples; having a selfless desire to serve the disciple, even to the point of sacrificing their own body; and treating all, both small and great, as equals. As Chapter 48 describes, a Sadguru sees the disciple as the Supreme Brahman, has fatherly love for them, and their dwelling is a storehouse of supreme peace, devoid of any pride in scholarship.