Does anyone know if the hard plastic cover on the back of the front buckets be purchased separately from the seat? Need to replace it.

 

Yes, it can removed. It's hard to remove without breaking tabs on the sides.

 

is it held with plastic clips or adhesive? Which tabs? other plastic covers for the back adjuster or the one below it.

 

This is a driver seat. You can see three plastic tabs on the side of the back cover that's near the center console. Those break really easily. There are also tabs on the door side, and some at the top. There are also 2 clips on the bottom, these are similar to the regular clips used in interior plastic panels. Part 23 is a bottom clip.

No adhesive used.