I modified a plastic funnel I had in the kitchen to fit snugly into the hopper. The fit worked out perfectly. The hole at the bottom of the funnel is nearly the exact diameter as the top opening of the grind chamber, and the upper diameter of the funnel is a snug fit into the existing hopper, about 1" down from the top of the hopper.
I had high hopes for this mod, but was let down. The funnel improved the consistency of the motor speed a little, but did not completely solve the problem. The motor still 'runs away' once or twice while grinding a shot. Especially with Vivace beans.
I experimented with stirring the beans in the hopper during the grind, and voila, problem solved! I stir with the wood handled teasing needle I use for WDT. I put the tip of the needle very close to the mouth of the grind chamber and stir in small circles, a little smaller than diameter of the grind chamber. Doing so makes the grind (and motor speed) much more consistent.
I have not tried this technique without the funnel in place, but I don't see any reason why it wouldn't work just as well.

[update]
I've done some additional experimentation and found that stirring during the grind (I've only tried it with the funnel) eliminates the motor speed fluctuation, but the amount of beans in the hopper still has a noticeable affect on the fluffiness of the grind. More beans = less fluffy. Fewer beans = more fluffy. The good news is it is consistent!
Hum, could this 'feature' allow you to fine tune the fluffiness of your grind?



