I did the same thing as you. It has definitely improved it does hit much more consistently now. But I still get the odd problem, separating the two parts and putting them back together usually resolves it. My guess is there are small differences in the machining and a few of us ended up with a combination of upper and lower parts that don't mate up quite as well as others.
Most of the tips to get these working seem to be related to the 510, button and firing spring. The negative connection is just as important.
I have other options that are just less hassle to use on a daily basis, they work without the constant fettling. But they should they were much more expensive. My CV is a backup so for 30$ it was a reasonable buy. If you get one of the good ones then it's an awesome buy.
Send it back if it is not a "good one" , FT has a 45 day money back guarantee . I would never accept something that i wasn't satisfied with.