The "always mount a scratch monkey" account, at https://www.cs.utah.edu/~elb/folklore/scrtch.monkey , is a very corrupted version of the story. See https://edp.org/monkey.htm .

There was no "Mabel", no swimming, and no asphyxiation. The electrical shocks caused all five monkeys to convulse, and three died.

This re-telling papers over the tragedy of what happened, both for the monkeys and for the service engineer who unknowing harmed and killed them.