Drop link play has no real effect on handling or steering, they just knock randomly as the roll bar twists through the level position, or while the car is level they knock over bumps. Load the roll bar while in a corner and the play is taken up and the knock disappears.
If the knock is triggered by turning the steering to the left, or while the steering is left of centre in a certain position, I'd say not drop links.
But it's easy to test drop links for play. Both wheels must be off the floor, grab the roll bar as close the end by the drop link as you can and pull up and down. You'll feel any play.
Roll bar MUST be level though. If its twisted by jacking ones side of the car only, the roll bar will be loaded and the play will be taken up. Due to the torsion of the roll bar, which is massive, it's then impossible to feel the play as described as described above.
Your symptoms sound almost similar AA's at this stage.