Is it actual blade play or just lock flex as they are not the same thing ? Lock flex is not seen as an issue that will cause the lock to fail through normal use and it can be found on pretty much every liner or frame lock to one extent or another. You can easily see it on the likes of an Umnumzaan, whith the knife opened and locked you can get the studs to just move off the frame showing what may look like play. It is only detectable visualy and is not movement that can be felt as there are still the same forces holding the blade in place. Actual blade play with be a back and forth movement on a particular plane that can be felt, seen and/or even heard as there are two surfaces being seperated and moved back together.