[Nonfractal]

...had replaced the gears with Slot.Its cos the alloy ones were wearing away fast. 
...NSR cars were roundly beaten by a Scaly Williams fitted with an Amato printed chassis.

Ken, 
My early attempts at living with NSR inline contrates yielded the same result. Alloy spray up the inside of the bodywork which continued until the contrate eventually failed. At that point I moved to Slot.IT brass inline crowns.
However, even Slot.IT contrates will eventually fail if the motor spindle is not prevented from grinding away the facing boss. 
It's always good practice to use stoppers to prevent excess lateral movement of the crown.
For the 86/89 NSR have installed axle tubes. If the wheels are installed correctly, they prevent the boss being worn away. 
Out of the factory, mine were set perfectly. 

I don't see the NSRs beating AllSlotCars in their first week either but as they evolve with suspension, chassis options, lightweight components and motor upgrades, I see the writing on the wall for most other marques.
Alan