Are the eccentric cranks on the Key model held in place only by the pressure of the nut?
On the two Sunset/3rd Rail engines I own, the position of the eccentric cranks is determined by a narrow tab cast into the back face of each crank (like a "key") that fits into a slot in the main crankpin. This seems like a pretty secure arrangement, as long as the slot in the main crankpin is in the right place when it leaves the factory.
