If you smoker is on a circuit that has a lot of other appliances running, your smoker may not be getting the proper voltage to run at 625 watts. Keep the generator on during the full cook. That will give you and additional 125 watts.
An average of 200°F is within the Bradley normal operating range. Heat does rise, but also does evaporated moisture. By placing the probe just above the turkey, or even near it, you will get a lower reading. Moisture is evaporating from the turkey, or any meat for that matter. Evaporation can bring the temperature near the turkey's surface, or other meat as much as 40°F.
You stated you never got above 200°F; even during seasoning, but you also reported that your thermopro was showing a reading of 220°F at some point prior to loading the turkey. I would go with the thermopro reading and move the probe to where I suggested. It is also unusual for no noticeable change in temperature, when the top vent is adjusted. I think you should keep a written log, and record what is going on during your smokes. A lot of things are happening, and recording them as they happen give you a clearer view of what is happening and when.
Though your bisquettes are burning like most members, sometime the burn rate is effected by too much humidity, the type of bisquettes you are burning, the set temperature inside the cabinet, and/or how much compression was used during the manufacture of the bisquettes. Three or less hours of smoke for turkey is what most members use. I generally will use maple, and add 2:40 hours of smoke.