It would be unusual that the aluminum clamping parts would "bend" or "bow"... aluminum doesn't really do that. Unlike steel, which is a pretty ductile metal, aluminum is not. May want to take a look at all the threads of the parts in the clamping stackup... it's possible that the small portion of the threads that are mostly highly used when you clamp things down.. those threads have been wallowed out due to the rocking back and forth of the seat when things weren't synched up tight enough. Usually, the first few threads take about 80% of so of the load, so if they are gone, things wouldn't stay where they need to be.