Riser Claw

Stop a cat scratching carpet?

I have a 1yr old cat and a 20yr old cat, both scratch the carpets on the bottom riser of the stairs and around the fireplace. I have used double sided sticky tape around the fireplace and the riser on the stairs. This has prevented them from scratching in these places but they have moved on to other areas of the carpet. There are 2 large scratching posts, both sprayed regulary with catnip sprays and cat nip dusted aroud the base. We have 2 other cats which use these, not fussy which one they use. The young cat and the older cat refuse to use them. The young cat is a house cat due to her petite size and the old cat does go out, though not as often or for as long as the other two. When he is out he does scratch the trees and fences, but still returns and wreaks havoc with the carpets.
I have read that citrus smells may prevent them from scratching the carpets, does anyone have any further advice?
I won’t trim their claws as reading about this can have a bad effect on the cat.

Some ideas:

1 Flat, disposable scratching boards.

2 Cat repellent spray for the carpet.

3 Trim the front claw tips monthly (different from de-clawing). My cats were annoyed with this at first but it saves furniture and actually is kind–without trims, my mom’s cat had an ingrown claw that had to be surgically removed.

BP Oil spill – preparing riser for amputation – cut off rope