help needed

Hi, Sorry to hear, just for clarification, it’s when you’re already in reverse and you let the Clutch out you hear this “pop”, not when trying to engage reverse, Clutch depressed?
Has it ever jumped out of reverse when letting out the Clutch, does it feel “notchy” when engaging reverse gear, or does your Trans exhibit any other anomalies in any gear but reverse, and does temperature factor in to occurrence, ie; Outside or Car Temp?
Do you have an adjustable Clutch Cable boss on your firewall?
Thank you!
John