will changing the transfer case fluid resolve a transfer case problem?

Car slips on gears 2-5. i am told it is a bad tranfer case. Porsche recommends a 5k fix of replacing transfer case. I have read that changing the transfer fluid may solve the issue but porsche dealership in Greenwich doesn't want to do this and recommends a 5k fix. Any guidance on whether changing teh tranfer fluid on a 2014 Cayenee would help?  this is a common issue with Porsche years 2011-2017. Is Porsche doing anything about their faulty transfer case that are bult incorrectly?