Unnop san and Nattawut san
Both "washing slide-way" and "renew connector" as you mentioned were not "prevent recurrence".
Those are merely "containment action" and those are a job of operator.
The domain of an engineer is "analysis root cause" and take appropriate "prevent recurrence".
So you and all engineers have to practice to use 8D report format.
and I am requesting all of engineer use that method more fluently.
Reporting by free format is required to be very high skill and it is too early for you in this moment.