ET: Engine (Twin) Thumb Wheel - Which is ‘Correct’?

[Alyson]

I have three battery post thumb wheels, all slightly differ from each other. I'm wondering if anyone can offer insight to any/all of these ? As shown below, I'll call the first one knurled, and the second and third reeded edged. All slightly different from each other and the middle one is stamped with the part number, making me think it's the correct one. Thank You in advance, Alyson

 

[Michael Vane-Hunt]

Mine are like the middle one.

 

[Simon Dinsdale]

1st one on the left with cross hatch knurl is a homemade one.
Middle one is what most series B & C machines were fitted with when new so is the most common type.
Far right one with larger chamfer to the knurl could be off a very early series B.

 

[chankly bore]

I believe some spares suppliers supplied cross-hatched thumbwheels and chain adjuster heads- all wrong of course, as are petrol caps with a similar edge finish. as an aside, the latest T27L oil tank caps are rougher than hessian underwear, or maybe they just send the crap to the Colonies!