Look at it this way, if you are a company that has an item returned to you, by a customer for a specific reason. What would you do, send them a replacement with the exact same issue, or check throughly that the replacement can't have that issue? Even if the company felt the consumer was being overly picky, I would think they'd make sure that the item was an example the consumer would be happy with. At least that's how most companies operate, that want to try to please even the most difficult customers. And yes many will go out of their way to try to please the people that they rely on to purchase their products.
So no matter what anyone says, ZT should have taken time to check thoroughly this replacement was without the issue that caused dissatisfaction in the first place. It's not like it takes much effort to pick a knife out that, has lock up that can't be pushed over with finger pressure mail it back and be done with it. And yes it could have been done that way, I have 4 ZT's that I can't get the lock bar to move on at all. Other posters say their 0801's can't be pushed over 100%, so why not just check and mail the customer back what they want? At least that seems the simple solution to me.