Front seat release flip handle no function

My car is a convertible. The very top seat release/tilt/flip handle moves without any tension and no function. So exit from the back seat is not convenient since the lower lever is not easy to reach for the back seat passenger.
Even entering the back seats by pulling the lower lever is not convenient since it has no memory function. I assume there will be some rod or cable disconnected. Can anybody tell me how to fix it?
Will I need to remove the plastic cover on the top of the seat rest for repair? How do I remove it? Thanks for your help!
Michael