Unfortunately, as far as we are aware, there is no repair options for these Power Supplies. It does sound like it is either failing or has failed and I would be cautious of leaving it plugged in if it is quite warm due to the risk of fire hazard. As for the cause, in most cases it is power surges, typically when there are power outages. However, there also can be resistors or other parts inside which become weak over time and fail.