I recall reading that Robert Morse had an ensemble member “assistant” kind of guiding him to his marks as the Wizard.
An inverse of being fired: for a bit of time towards the middle of Rent’s run a Roger allegedly went to rehab, and either the producers or stage management opted to not replace him, but alternate understudies for the remainder of his contract.
"Grease," the fourth revival of the season, is the worst show in the history of theater and represents an unparalleled assault on Western civilization and its values. - Michael Reidel