Ah so! I get the same thing on my Quest with the ET probe, which is a loose fit through a drilled out cap screw. The same solution as yours, by the way...ground the probe. Anyway, back to the intent of your thread, over time I've come up with my own dark roast profile, which suit my tastes. But it's not far off from what I understand of Rao's work. I preheat fairly hot (given you can't really do this on a fluid bed), start with a high delta-BT (ROR). My BT ROR from charge (~ 200 C), through Turning point (~ 110 C), to dry (~150 C) can be up to about 12 C/min. Considering only the part of the curve from TP to dry (so more like on a fluid bed), ROR would be closer to 14 C/min). I shoot for about 25% of the overall time to get to dry, about 1.5 minutes of which is the temp drop from charge to TP (not sure to think about this for a fluid bed). There's a point between dry and 1C (can't even define what the heck it is other than some sort of 'sweet spot' I've found), where I back off on the heat, allowing the ROR to drop. Over all, the ROR during this phase is about 4 C/min, changing from ~12 C/min at dry end to ~ 2 C/min by the time I've hit 1C. Overall time for me at this point is about 75%. ROR continues to lower only a bit to 2C, which is where I generally drop the roast. I try not to let it drop much below ~ 2C/min; although If I mess up I sometimes have to increase the ROR a bit (maybe up to ~4 C/min) to achieve my desired temperature at the right time. What I do for most greens is about the same, except for certain beans, such as very large/light ones (e.g., monsooned Malabar), or very dense/small ones (e.g., pea berries). I have not really figured how to roast these two extremes yet, as I roast them so infrequently.

Getting better: