I can't tell you how many different ways I have made falafel fall apart. From my misadventures, I have gleaned a few tips. 1. Use a binding agent - a little egg and/or some flour. 2. Drain all ingredients completely. Avoid excess liquid. 3. Roll the balls around in your hand a little while to develop a smooth surface. I guess this would activate the gluten. Just pressing a little ball together doesn't work for me. If they're falling apart change something - add more flour, roll more. My batches usually start with something wrong the first few falafel, but by the time I'm into the process they're turning out well.