George - Write the letter.
You need a qualified inspection of the installation and components.
Or, I suppose you could let any warranty expire and not get any satisfaction. You may have multiple problems. Look at it this way- for as much as I loathe the service of this company and that they essentially R&D'd models in peoples homes I have one of these same models you have and I have to say it works and I don't have any of your problems. That points to installation in my mind unless you have a physical change/defect in your specific unit. Your exhaust fan needs to be check for proper capacity (speed). Your feed rate needs to be examined. The circulation blower needs to be checked...temperature rise across the unit....
BTW- extra surface contact on the snap disk is not the issue. Usually the parameters for that aren't that tight and it's setup so that if it's good and it trips you definitively have another issue.