A couple of comments after reading the 11 pages over there, those shiny contacts are not brass, that's
GOLD so it won't corrode, and those carbon film resistors are actually deposited on that circuit board and then etched similar to the way fine features are etched on silicon wafers to make ICs. (I know all about that stuff since that is what I do for a living!
Resistance = (rho * L)/A where rho is the resistivity of a given material, L is length of the material, and A is cross-sectional area of the material.
What happens is when the brushes are over the place where the carbon film is over the gold, any slight change in L there is neglible because A in the equation above is huge. However, once you move off of the gold pad and onto the resistor track, then the A becomes the cross-sectional area of that thin film of carbon (very tiny) and that is significantly different as L changes.
I am going to remove mine and see if I can put in a thottle stop that does the same thing. I am pretty sure this is what is annoying the hell out of me in traffic since you have to ease into the throttle say at a red light, stop sign, or stop-n-go traffic.
A very nice piece of info and we need "tube" over here for sure!
I have to admit that those 11 pages are sort of entertaining, but having to read stuff like that all the time over there is why I bid them adieu!
Mike