mptubbs,
Sorry you are having problems. A lot of good suggestions have already been broght forward.
My six rack digital is not very dependable as far as the set temperature matching the actual temperature. I do not rely on the set temperature to get the heat up. I crank it up to 250 or a little higher. Then I wait until the actual temperature on a Maverick chamber probe on the bottom meat rack hits my target temperature. The probe is on the door side. At that point, I adjust the Bradley set point down in ten or twenty degree increments until the Maverick chamber temperature settles into the proper range. Usually, my digital readout is at 240 to achieve a true 20 -225 temperature and hold there. You have to interpolate a little.
If in doubt, open the door and see if the heat element is glowing to make sure the thermostat hasn't shut you down.
With your one degree climb per hour, the thermostat may have been clicking on and off. The chamber temperature was not as hot as you thought but it was hot enough to slowly raise the chicken temperature which allowed the chamber temperature to rise slowly.
For preheating and temperature hold, I replace the water pan with a half size steam table aluminum pan full of boiling water laced with your favorite additives if any. As others have stated, preheat to 250 or more and most of the time let the meat heat up to higher than refrigerator temperature before placing in the Bradley.
One other comment. Because the element is in back and the temperature thermostat reading device is in the back, heat rises across the back and fools the digital into thinking that the temperature is high enough. I loosely foil the back half of the vent/drip rack to force more heat forward which seems to balance things out better. Classic Rock Griller recently reported on opening the front vents and closing down the back vents some. That may be another solution.
This link will have a photo of almost 50 lbs of meat and the foil pan, foil covering and hot water technique. The photos you are looking for are down a ways.
http://forum.bradleysmoker.com/index.php?topic=12061.0The Bradley is slow but it works well when you get to know it.
Good luck and slow smoking,
Pachanga