In April 1940, the Bangalore mast ashram was disbanded and some of the masts were brought here. An enclosure of bamboo was added and this became the main area for the mast ashram at Upper Meherabad. As in the Bangalore ashram, Baba even provided a chai and a beedi shop for them. As World War II became more serious, from June 1st Baba began doing seclusion work here with the masts, most notably the mild-mannered Chatti Baba from south India. During July 1940, Baba had Pendu build the Cage Room to accommodate the "tiger mast", Karim Baba from Calcutta. Besides Krishna and Vishnu who had duties to serve Baba during His seclusion work here, only Mehera and Mani were allowed to occasionally greet Him at the south window of the Cage Room. An opening in that window that allowed messages and mail to be passed in can still be found.

When Baba was in seclusion here, Krishna Nair served as His personal attendant, spending most of his time on watch outside the gate. Above the gate there is a bell that was used to signal permission to enter – by Baba from the inside or by the attendant outside. Baba would hide Himself in the room before Krishna entered for any particular duty. One day Krishna heard the bell ring, but Baba had not rung it. When Krishna entered the compound, he "beheld Baba emitting the light of a 100 suns". Krishna began to lose consciousness when Baba quickly grabbed his left bicep and forcefully tore the muscle causing severe pain. The physical shock saved Krishna's life, and the scar he bore for the rest of his life served as a reminder of this incident and the power of Meher Baba's seclusion work.

During September 1940, two toilets and a bathroom addition were constructed, and the compound of bamboo matting was replaced with the corrugated steel sheets that are still there. During that time Baba was occasionally engaged in seclusion work with masts, and this enclosure provided the main area for the mast ashram in Upper Meherabad. Baba even provided a chai and beedi shop for the masts’ use. The mad ashram was also moved here for a short time then before it was disbanded. In preparation for another special seclusion beginning August 1st 1941, Padri cut a small opening in the Cage Room so that Baba could communicate with His attendant.