I have a 2006 Harman accentra that has been run every season...maybe I have gone through 15 tons of pellets in 7 years. when I started using the stove this season, I notice that my temperature setting seems off. when I set the stove control to "room temperature" of 70..the room only makes it to about 62 degrees. If i want a 75 degree room, i have to set the control to 80. It seems that the temperature control is 5 to 8 degrees off. In the past, this control was right on the money..within a degree or two. Could it be that the probe end is "dirty" and needs cleaning? or is this a sign that the sensing bulb is failing? So what do i replace...just the sensing bulb and wires? or the plug too at the back of the stove? The sensing bulb has been located on the wall behind the stove in the same spot.