[Nonfractal]

A long time since I OPd this thread.
I made several references to "diligent preparation" during the discussions above.
When preparing a pair of NSR corvettes for racing g at NascotWood (tomorrow) I made some mental notes of the preparation process.

Flossing:
Dirt ingress always occurs on gears.
Some lubricants attrract and hold more that others but one way or another dirt will accumulate, especially in the tooth gap. 
When dirt sits in the inter tooth gap, It will eventually begin to get compresed by the opposing tooth.
When that compression occurs,the gears will not run smoothly and you will eventually get to a position where you have a notch in the cycle of the gears. 
I use zippo and a toothbrush initially which is normally enough to remove the debris.
An ultrasonic cleaner can also be very useful to get dirt out of gears. 
If zippo and ultrasonics do not work, tooth floss (honestly) or in the extreme, a scalpel will be needed to scrape out the dirt. 
When the gears are clean and will formed and the backlash is set correctly, there should be no perceptible "notches" felt in the gear's cycle.
Many ask me how my cars run so quietly, now you know 
Alan

PS 
Tamar re :  DiSCA gearing. 
I don't think your explanation works.
PWM controllers (like the SCP2) use the same method as the on board digital chip to  control power delivery, yet switching between a resistor controller and an SCP has no impact on gearing (that I can perceive)
However, I don't have an alternative explaination for the reason that DiSCA cars are geared the way  they are. 
Maybe the on board chip has some characteristics that neither of us know about.
Only Maurizio could explain this I suspect.