I think where I don't have a pressure problem is my type of machine- it isn't the 'clam' type. Its a huge old heavy yellow monster-with a double 'shaft' right in the middle and a 'U' bar handle. Funky double cam hinges when you press down and the swivel on the post in back has a T handle you lift and move around to different 'holes' in the post for pressure. So all the pressure is applied to the 'center' area of the platen-and with it being solid steel-there's not much that would keep it from sitting level. I can see how lighter platens or an off set hinge can do that-and I've had it happen if a collar folds up under and we don't catch it. Having caught my fingers underneath this (not with heat on) I know it really can crush down! Roland