People may warn of over kneading but not enough can be a problem also. Always better done by hand, to get a feel for it, the dough should be "elastic" or "strechy". It should pull quite a bit without cracking and then be properly rested where it will become "softer" feeling. By hand with 3 or 4 lbs of dough the kneading can take 20 minutes or more, and the resting another half hour. My pasta machine gets thinner as the numbers go up so numbers are meaningless but the second to least thinnest works for us it's 7 out of 9. If it's hard to handle when you roll it out, hang it over something to dry for 5 to 10 minutes. When they loose that sticky shine and the edges start to feel "leathery" they should be easier to work with.