It would also be worth checking to see if some old lubricant has congealed or solidified under the magazine catch. This could literally "gum up" the operation of this part, and keep it stuck down.
If you are considering polishing the well where you circled things in the photo, you'll probably need to remove the hold open anyway. Just use care to not break the thin spring at the tail of the part. Check the drawings to determine the right motion to remove the hold open.
Because of the operation of this part, it "takes a licking and keeps on ticking" every time it operates, getting slammed into the circled area of your photo. These are hardened metal surfaces, but might require some gentle polishing.
Marc
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 Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.
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