I removed the carpet and step on my 1121 when I put a marine hatch cover in the top of my water tank, and I eventually had to give up on getting the carpet off without damaging it. The staples Lance uses to fasten the carpet down are TINY little fine-wire things that you will never find. Plus, there's about 1000 of them just holding that one piece of carpet down.
Rip the carpet off, then you will see the screws holding the plywood down. Then find a remnant that complements the decor and recover it.
:):)