Can a turbo be repaired?

Could you elaborate on the feasibility of repairing a turbocharger? Are there specific components within a turbo that are prone to wear and tear, and if so, are they replaceable? Furthermore, is it advisable to attempt a DIY repair or is it more practical to seek professional assistance? What factors should one consider in determining the cost-effectiveness of a turbo repair versus a replacement? And finally, are there any safety concerns that arise when dealing with the high-pressure and high-temperature environment of a turbocharger?