Rust? Inside Nespresso D150

I picked up a D150 the other day and disassembled it to clean. Where the capsule cage/needle screws into on the machine (not sure what to call it), I noticed what appears to be rust. I've tried cleaning this, but with no luck. Any thoughts on it being safe to use as is or ways to clean it out? I'm not sure if it's even technically rust or something else. If parts were to chip off, I'm not sure it would even make it through the needle? TIA