The 7693 seems to put more pressure on the plunger than the 7673 did. We had one that was bending plungers, but the syringes seemed to be defective, they would become very stiff after only a few days, a new box of syringes solved that problem.
How soon after installing a new syringe does it bend?
It might be a good idea to remove the syringe every day and wipe the plunger with a damp Kimwipe and even use another to inject some water into the top of the syringe then push it through with the plunger, as some sample can escape up the sides of the plunger and if the water evaporates can become sticky and make the plunger difficult to move.