Well I went back and did barbell squats, body weight plus 5% for 3 sets of ten reps. Didn't want to wear myself out. I tried 1 rep of front squats and it felt weird pulling my wrists backwards. Surely that can't be good especially if it's loaded. And then if I crossed my arms, the bar would just cut into them. I guess my arms are still too thin.
Then my regular sitting leg curls, 3 sets of 18 to failure. And hack squats.
I had written to Technogym and asked what the weight or starting resistance of the empty carriage was. No response. Anyways I started with zero weights, then two 10lb plates, then 15 lb, then 20 for 15 reps each to get the feel of going deep.