I had the same problem with my seat. When climbing steep and rough uphill sometimes it would slide all the way back.
For a while I just put some wedges under the tabs to force them into the slots. Later I just switched the passenger and driverside seat parts. No more slip but the recline lever is on the wrong side. Not a big deal, sort of like having the ignition switch on the left side of the steering column.
The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. -Thomas Jefferson