Acrosport 11
It was a wear problem. Most high time Cessnas have had their seat rails replaced at least once. Cessna just a few years ago gave the secondary stops out free. My C210 has one fitted and it works well.
SEB07-5 Rev 5 provides for the installation of a secondary seat stop under the pilot’s and copilot’s seats. It looks a lot like a seatbelt reel attached to the bottom of the seat. The end of the belt is attached to the cabin floor. The reel has a release mechanism that is activated by the same lever the pilot lifts to release the latching pins.
I believe the New Start Cessnas have a different rails. The top of the rail is smooth where the rollers run and the positioning holes for the lock pin are in the side of the rail. The new style rails should have a much longer life.