The second row driver's side seat belt on my 2017 Discovery is stuck in the retracted position and will not extend. I believe this is called "reverse lock"? I have tried to pull the seat belt out as much as possible and then let it back in to break the reverse lock, but it has not worked. I have snaked a camera into the wall and the seat belt is not tangled going into the retractor. How can I fix this?

 

I know you're here for advice on a quick, do-it-yourself remedy, but are you still under warranty?

Seat belts are not something I'd want to try and "fix" and not be 100% certain it was ready to function correctly when needed.

 

I agree completely.
Also, I had the front passenger seat belt lock up numerous times when just driving normally. Had to retract it completely and pull it back out to get it to release. Dealer said it should react exactly the same as the drivers seat belt, but it did not, it was way more sensitive.
First attempt to fix it by dealer said they'd try to adjust it. I was skeptical but let them try. Didn't fix it so I asked for a new one and got it on my next service visit. Hasn't had a problem since.