First off, I have really been enjoying working with the DM42! Moreover, my experience with SwissMicros has been outstanding, and I will be recommending their calculators to everyone I think might be interested. I very much appreciate the online forum as well.
Yes, both of our DM42's have the same enter key behavior. The left side registers but does not click or depress much. My machine was much worse with regard to this issue. I eventually ended up peeling up the tape and replacing the enter key domes with domes from less used keys. I am hoping that this does not cause future problems. But the tactile response of the enter key is now quite good. Comparable, if not better than my wife's machine. Although still, the enter key does not click when pressing the left side of the key.
In an effort to improve the key feel throughout the entire keyboard, I disassembled the calculator and tried bending the keys inwards and outwards to loosen the plastic attachments of the keys to the front-plate. The result is that my keys are now considerably less angled, but the key presses are easier. I think it feels better.
Mine also had the problem of the opposite side of the machine lifting off a flat surface when pressing keys in the leftmost or rightmost columns. I emailed SM and received a quick reply with instructions to try stepping on the back of the fully assembled calculator, as well as to try twisting the assembled calculator diagonally. Well, I was very happy to correct the issue to near perfection by following those directions.
For now, I think the hardware aspect of my machine is in good order. I look forward to using it lots.