I rebuilt my driver's seat. It's not a hard project, especially if you can drive a sewing machine. You will need hog ring pliers and rings, a donor seat for foam (doesn't need to be Delica); and some 3M77 spray glue. The process goes like this:
1) disassemble the seat from the back and bottom rails
2) clip and remove all the hog rings from the underside and then from the topside
3) assess/repair the frame (probably a broken weld or two)
4) cut back the worn foam on the seat bun and reconstruct from your donor. An electric carving knife is the tool of choice.
5) repair the seat cover- here you will want matching fabric. I sacrificed one headrest for the material needed- slice it following the seams and then tear the two pieces off the foam; it's put together like a baseball. Unfortunately, I had to scab together two the two pieces to get a piece long enough- and the underside had aged differently.
6) reassemble with new wires (sturdy coat hanger works great) and hog rings
Also, use scrap material and spray glue to reinforce any thin areas on the underside before putting it back together.
Of course- take lots of photos and notes along the way- the install sequence is important to get the nice factory tucks in the seat since you will be hog-ringing the internal support wires to the frame
I can put together a more detailed post if it would help; I have more photos of the process.
Befores and afters:
