Help: blade play on my delica

[todapoint]

I am experiencing a problem with my delica 4 lock up. When I open the blade and push down on the thumb ramp the blade can move down a click and the lock bar seems to go in further and then when I put pressure upwards on the blade, like when cutting, it clicks back up a click and it can do this back and forth. It kind of seems like the lock face isn't sitting flush into the cut out in the tang of the blade. The click is a very small distance but enough to feel. I was wondering what I can do to fix this

 

[Nenum]

My Delica 4 showed the same behavior when I purchased it. However, after taking it apart to clean and lube, it seemed to fix the issue for a while. Now it's gone back to the way it was after a few weeks of pocket carry.

I suspect maybe the dirt and lint is interfering with the smooth engagement of the lock bar.

 

[todapoint]

I think I fixed it, its pretty tight right now