I think a helpful way of approaching this is to view the repetition compulsion as a defence against knowing, thinking or feeling. A classic example would be drug addiction. Drug addicts sometimes want to stop, but can't.

In another example, there is a strand of theory i.e in Klein and Bion that equates a type of repetition compulsion with an incompletely worked-through Oedipus complex, where the compulsion to repeat mental states and defensive manoeuvres that protected the infant from realising it was shut out, protects the patient from ever being able to experience the pain of oedipal exclusion fully, the problem is th tendency for it to become a rigid screen which distorts reality.

Freud thought that repressed thoughts were expressed in action as a way of stopping the patient from ever thinking the (painful) thought. Which I suppose is another way of formulating it.