Sridhara Swami, Bhavarta dipika commentary to SB 1.1.1 > CC 2.17.80:

mUkaM karoti vAcAlaM
paNguM laNghayate girim 
yat-kRpA tam ahaM vande
ZrI-guruM dIna-tAriNam

"I offer my respectful obeisances unto my spiritual master, who is the deliverer of the fallen souls and by whose mercy a dumb man can speak eloquently and a lame man can cross mountains."

variations
- CCAntya 3.1.1:

paNguM laNghayate ZailaM
mUkam Avartayec chrutim
yat-kRpA tam ahaM vande
kRSNa-caitanyam IZvaram

SYNONYMS
paNgum—one who is lame; laNghayate—causes to cross over; Zailam—a mountain; mUkam—one who is dumb; Avartayet—can cause to recite; Zrutim—Vedic literature; yat-kRpA—the mercy of whom; tam—unto Him; aham—I; vande—offer obeisances; kRSNa-caitanyam—ZrI Caitanya MahAprabhu, who is KRSNa Himself; IZvaram—the Lord.

TRANSLATION
I offer my respectful obeisances to Zri KRSNa Caitanya MahAprabhu, by whose mercy even a lame man can cross over a mountain and a dumb man recite Vedic literature.

- Sankara, "Meditation on th Bhagavad-gita" 8 (quoted in SSR 3)

- Isaiah 35:6:

4 Say to them that are of a fearful heart, Be strong, fear not: behold, your God will come with vengeance, even God with a recompence; he will come and save you. 
5 Then the eyes of the blind shall be opened, and the ears of the deaf shall be unstopped. 
6 Then shall the lame man leap as an hart, and the tongue of the dumb sing: for in the wilderness shall waters break out, and streams in the desert. 


The mystery of empowerment

Empowerment comes with a humble submission to the authority of guru. In the presence of guru one becomes suddenlly humbled by ignorance and incompetence and while in a position to teach others, empowerment comes in the same way. And one gets the responsibility to properly represent one's guru.


Attitudes toward guru

Srila Prabhupada, VaiZiSTyASTakam 4.40 (1961):

"The one who renounces his guru’s order (guru-tyagi) and the one who tries to enjoy the assets of his spiritual master (guru-bhogi) are two kinds of useless persons. First become a servant of your spiritual master (guru-sevi), and then you will understand all these things clearly.

guru aparadhi - vikarma
guru bhogi - karma
guru tyagi - jnana (impers.) > all three asara
guru sevi - bhakti > empowerment


Three types of gurus

1. vaidika - represented by Vyasa 
("Vyasadeva is the original guru (spiritual master) of all who follow the Vedic principles," CC 1.17.16 p.)

2. vaisnava - represented by Sri Baladeva (Adi guru)
("Balarama is presenting Krsna, and therefore He is the original guru. Any bona fide guru must be a representative of Balarama, or Nityananda.", SP lecture, Mayapur, March 26, 1975)

3. rasika - represented by Sri Radha 
(rAdhikAra prema—guru, Ami—ziSya naTa, CC 1.4.124)


When the guru feels he cannot teach his disciple more, he should refer him to a more qualified siksa guru,
just like Hrdaya Caitanya sent Syamananda P. to Sri Jiva Gosvami.