I have posted several complain in the past about the first layer curve up sometime, and in some smaller parts, the head knock them over before the print gets finish.
I have received many advise, especially from jps8, about heath related possibility . I have even hired a shop to make me a glass build plate with conductive squares
as the original perforated plate. GLASS DON'T WORK !!!! I had more problem with glass, than with the original build plate. To make the long story short, I start testing
heath related solutions. Cower up the sides, level the plate, and made a plastic cower for the top. (Tall one, to accommodate the wires and ABS line).
It did help, how ever the problem did appeared again. Well, I got "upset, and try thinking" I have find a solution to the problem.
I have ordered enough woven ceramic strip insulator with adhesive, that cover up the bottom of the heath plate. This is about 50 mm wide insulator
that have heath resistant adhesive on one side. The heath can't escape as much, so the top stay warmer. IT's working !!! no more problem.
Again , Thank you for all your help. I'm a happy camper again.