In recent weeks I have come to the conclusion that private methods can be an indicator that a class needs to be refactored. The more lines a private method contains the stronger the indicator. Please be aware that I'm not arguing against private methods or that I consider them harmful, quite the contrary. A private method which encapsulates a condition to be used in another method of the class can be really helpful when it helps to keep the same level of abstraction in this other method.
However, such little methods seldom have more than 1 to 3 lines of code. When your private method starts to have five lines of code or more it becomes an indidator that it does things which shouldn't be done in this class in the first place. It should be done in one of the collaborators the class already has (i.e., one of its dependencies), either in a public method or as part of other operations in one of these collaborators. Alternatively, if it fits into none of those existing collaborators, it could give you a hint that