You could try this one.
When I got my D4 Wave, it also had side play.
Cause of this were the PB washers.
They are thicker then the previous nylon ones.
Now if the screws of the lockbar pivot are tightened, it disformed the handles.
Solution was to loosen both the blade pivot and the lockbar pivot.
Then tighten the blade pivot, till it is at the tension you like, and after that you tighten the lockbar pivot, but only lightly.
Just so that it won't loosen by itself.
I suggest, you give it a try.