My suggestion is similar to Jim's if I'm following. That said, the first thing I would do is measure the carcass and drawer to see if anything is out...
I'm not sure what your first question means. If I needed to shim the front out 3mm at one side I would use a 3mm shim strip at the front corner and a...
David, have you been re flattening iron every sharpening? I cant think of how it no longer will tighten properly unless the iron has gotten thinner....