Can you describe the instances where devotees experienced visions of Vitthal in Shirdi, according to the provided text?

The provided texts from Chapter 4 describe multiple instances of devotees experiencing visions of Vitthal. During a Name-week organized by Das Ganu, Sai Baba assured him that Vitthal would appear, provided the devotee was full of faith, and it is said Das Ganu did receive a sight of Vitthal. Another detailed account involves Kakasaheb Dixit, who had a vision of Vitthal during his morning meditation. When he later went for Baba's darshan, Baba cryptically asked if "Vitthal Patil had come," advising him to "nail him down." The vision was miraculously confirmed when a seller arrived with pictures of Vitthal, and one image was an exact replication of what Kakasaheb had seen in his meditation.