I don't understand the topic. Doesn't what PURSUE said imply that the machines have already killed him?
At any rate.
To use them properly, you need to perform the motions slowly and with proper form. As with any exercise, you must not bounce or jiggle. For machines this is doubly true, as the machine is already guiding your movement. With free weights, you devote more strength and energy than you'd realize just to keeping your limbs in their proper positions. On a machine, even a teensy amount of form cheating will render the exercise pointless.
Find a weight for the machine that you can comfortably and fairly easily do 15 reps on without shaking at all. Then move up gradually until you find a weight that you can do 10 reps of, still without shaking, but that gives your muscles that deep burning feeling.