[linux-audio-user] Gnome Wave Cleaner, muffled to normal?

I'm using the Gnome Wave Cleaner 0.20-07 to clean up an old LP before burning it to CD. I've very impressed with GWC. However, I do have one problem that GWC seems unable to solve. There is one area of a song that's muffled and I can't see any way to bring back the "brighness" to match the rest of the song. I guess its highs have been clipped in some way, probably from my blundering ( this is my first LP with GWC ) but from the screen I can't see any damage. I've tried the Edit->Amplify command, but though it gets louder, it's still muffled. And it's way to late to for the Undo command to help. Does anyone have any ideas how to return the brighness to a muffled section of a song? Would something like Audacity help? I've no experience with sound editors, so any information would be very welcome.