xiaoman1 

Clear-coat has often been used to protect the finish on chrome.....many bikes have it on their "socks". Older frames often have the appearance of dull chrome on them because of the clear deteriorating/aging. I have never had a problem removing the clear.....paint stripper and a wipe then a rinse is all that is typically necessary...no steel or brass wool ever, the chrome will be shiny after that.

Regarding the crack, if it is the clear, I would get some paint stripper and apply it to that small area and remove the "clear", if the edge disappears all is good, and no crack....if not then I would use an Exacto blade with the tip pointed down without scraping to see if the tip will go into the edge (hard to explain, but you get the idea), scraping will always give the feeling that there is a crack if the surrounding clear is not removed because of the edge, etc.

Seems suspicious to me because the edges are sharp/jagged unlike the ones on the blades, but stranger things have happened... hopefully, it's only clear.

Good Luck Best, Ben