Thanks to everyone for your precious pieces of advice. I will probably try to sell it with a small discount since there is a lot of MCP #72 with a 9.8 on eBay.
After a few weeks, I will give it a bigger discount, and after a few months, I will try to auction it using lostboys strategy.
I always do that when there is something wrong with the comic or the case. Last year, it was a hair between the case and the inner well.
I should have specified that the spine tick breaks colour. Unfortunately pressing wouldn't change anything.
I put the slab under the light and give it the right angle and the spine tick show up. See for yourself (picture below).