Don't listen to these guys - take a chainsaw to that puppy and field strip it!
Seriously though, if yer REALLY worried about the scratched mount, here's food for thought. Is it just an appearance thing, like surface scratches? Or is it gouged, as in you had grains of sand on there when you mounted a lens. I suspect it's just appearance. You could try polishing, but only if it's something that will keep you awake at night. Practice on the extension tube with a cotton swab (Q-tip) and a small dab of metal polish like Brasso. Be careful, even if it works, when you do it to the camera you might use too much and it might drip into the camera body. Plus the whole time you're doing this, dust is falling into the camera body. My point is, cosmetic mount scratches are nothing to worry about. Put that OCD on the shelf and take some photos. And put your extension tube back together, it's fine.