How does Chapter 10 describe the role and power of a Sadguru in a devotee's life?

According to Chapter 10, the Sadguru is paramount, described as the "one eternal God" in contrast to other illusory gods. By placing faith in the Guru's feet, a devotee can have their fate changed, an act metaphorically described as the Guru striking "a nail over the lines of destiny." The text from chunks 0 and 1 explains that pure service to the Sadguru can completely destroy the worldly existence (Samsara) and help a devotee overcome the three types of miseries. The Guru acts as a boatman to help cross the ocean of existence. Furthermore, the Sadguru's grace can destroy accumulated (Sanchit) and current (Kriyaman) karmas, break the knots of the heart, and grant liberation (Moksha) effortlessly to the faithful.