The usual 116 problem is a sagging outer edge to the drivers seat and the only real lasting solution is probably a new seat base and prefererably the older and interchangeable 108 type with coils springs rather than the later torsion bar type springing - very labour intensive and requires finding and purchasing a 108 (or early 116) seat base.
Another option is to change the passenger seat base for the driver seat base - also very labour intensive.
When I re-upholstered my front seats 2...