The replacement pinions that Alan sells ‘look’ good. I have not installed one on my spare motor, but the teeth/vanes are nice and Pineapple/Coke-bottle shaped and with a dry fit outside the car appear to mesh well with the spur. They also have a little ‘well’ on each end for a drop of Loctite Red or solder. They are 6.4mm in diameter but have the rounded tip instead of the skinny sharp tip that Alan recommended rounding off (from the OEM 6.7m pinion).
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This is the OEM replacement from Pendle – appears to be what Alan sells (he appears out of stock today). 6.4mm OD – thick teeth P/N: RS212 RevoSlot Brass Pinion 12t 6.4mm
https://www.pendleslotracing.co.uk/spares/pinions.html?manufacturer=475
"... get on your bad motor scooter and ride!"
Sammy with Montrose