I have absolutely no expertise or knowledge of these coins ... so adding my comments as general observations of an experienced collector.
The scratch on the reverse shield was likely acquired many years ago ... and in my opinion does not detract from the coin in a very significant way.
Using accepted USA grading standards ... I estimate the coin to be in XF range ... based solely on the remaining devices and without knowledge of the series.
Quote:
I am afraid to use acetone on this coin, once I have used it on large cent and it doesn't looked good.
You did something wrong at that time ... perhaps not using pure acetone.

100% pure acetone is an effective and non-invasive way to remove organic material from a coins surface without damage.
Lovely coin ... thanks for sharing it with us!
David
Take a look at my other hobby ...
http://www.jk-dk.art