Q. It is explained that at the time of inititation, the Guru takes on all the karmas of the disciple. My queston is 2 parts:
a) is it a voluntary process that the spiritual master has the power to do, and he may or may not take the karmas of the disciple ?
– Ram Mahtani

A. The bona fide spiritual master is the bona fide representative of Krishna. Krishna is supremely pure (ref. Isopanishad mantra -8) and so if He accepts anyone’s karma, He is not affected. If someone surrenders to Krishna, He agrees to deliver the person of his sinful reactions (ref BG. 18.66), and yet He Himself is not affected by them. Since the spiritual master agrees to accept disciples, he accepts the role of Krishna, which includes the responsibility of accepting karma of those who surrender to him. So, whenever a spiritual master accepts a disciple, he accepts the karma of that particular disciple.

b) If the process of ‘taking on’ the karma is a voluntary process on the behalf of the spiritual master, will the spiritual master continue to relieve the disciple of further karmas too ?

Since this relationship between a spiritual master and his disciple is eternal, the spiritual master has to accept karma of his disciples till the time the disciple is successful in going back home, back to Godhead. And so, it is risky to accept disciples for initiation. Driven by compassion, for preaching purposes, a pure devotee of the Lord still accepts disciples to guide them back to Godhead. In reciprocation, Krishna protects His devotee but the disciple should always be careful not to cause any trouble to his spiritual master. It is the duty of the disciple to follow his vows taken during initiation strictly, because any non-compliance affects his spiritual master.