I have one of the first-generation pioneers, with the front-mounted lock release. My problem is that there is a slight amount of vertical blade play (maybe 2 mm) when the knife is open. This seems to not affect the lock strength, but does make me a little nervous. Anyone else have the same problem, or else a solution? About a year ago, the guys at Pioneer Valley Knife and Tool gave me a new backstop to try switching in, but that didn't help.