How do I clean these zippers of leather jacket?

[mayum1]

I bought this on a heavy discount brand new in an online store and they came to me with tarnished hardware.

Size is out of stock so they can't replace. They also assured me they do not sell seconds or non-authentic products. They have offered to refund but I like the jacket, plus I got it for almost just 40% of the original price.

Any idea on how to clean? Or do I just return for a refund.

Another pic

Another shot of the zipper

One more

Warning...I often go where angels fear to tread...but out of DH's eyeshot I would try wd40 on a cotton bud taking extreme care to not get any on the leather.

I'd spot test on the inside first.

I think it looks fine as it is...

Thanks! Maybe I am just being OC about this.

I think it looks absolutely fin, but I would start with a tiny bit of fairy liquid on a toothbrush (clears up a surprising amount of tarnish, fuck knows what's in it), then maybe try something like wd40, but the chances of wrecking the leather would probably put me off.