As the title says the Gimble Knob and C1 Back button do not work on my RC.  I was wondering what I would possible have to replace to get them working again.

Hello there Malkozaine. I am sorry for the trouble this has caused and thank you for reaching out. Since we are having this issue with your DJI Remote Controller. I would recommend you to contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for further assistance.  We will do our best to help and will give out the best resolution for this issue. Thank you.