Snip-the-tip mod for Dometic fridge

With all the bad press that rv fridges have recently received concerning their cooling abilities, I'm probably expecting to much. We had the "Amish" unit installed in our Dometic NDR1062 several months ago and it cooled rather well at first, with temps in the 33-36 degree range in the box, -5 to -10 in the freezer, when setting the outside panel on 3-4 out of 5. (2) four inch computer case fans were installed at the top of the roof vent and controlled by a rocker switch. Lately, the temps in the box only, using the same setting(s) have inched up to the 38-42 range in the box. Food is not being packed inside to restrict airflow, the door is left open only long enough to retrieve certain items and all door seals are snug. A new thermistor, burner and 325w heating element were installed at change over and the orifice was removed and cleaned. The lp burner has a good blue color when on and a slight noticeable burning sound. 24hrs prior to leaving, I go to the storage unit and turn the fridge on lp and 12-18 hrs later, the freezer is at -5 and the box is 38-40 so it appears to be cooling down correctly. It sounds like some investigative work is in order to make sure everyting was done correctly from the start, ie; installation and sealing. :h Maybe I'm expecting colder temps then are reasonable and thought the "Snip-the-tip" would help. Has anyone heard that the OEM boards used by Dometic are basically "set" for 40 degrees and the dinosaur boards have an adjustment so the temps can be lowered? Thanks everyone for your comments so far.;)