What are the most common issues with Audi's quattro all-wheel drive system and how can they be fixed?

I recently purchased a used Audi with the quattro all-wheel drive system and want to be prepared in case any problems arise. What are the most common issues with this system and how can they be resolved?

The most common issue with Audi's quattro all-wheel drive system is the failure of the transfer case, which can lead to loss of power to the wheels. To fix this, it is important to regularly check and replace the transfer case fluid and have it inspected by a certified mechanic.

Another common issue is the failure of the center differential, which can cause uneven tire wear and handling issues. To prevent this, make sure to rotate your tires regularly and have the differential checked and replaced if necessary.