First, if you look at the progression of the illustrated or exploded view drawing over the years from 1945 to 1976, you will find that the earlier ones tend not to show all of the commercial parts (like screws and pins) that are actually present. And in general, the assemblies seem to vary a little over the years. I and a member of another list who happened to have several 618 headstocks to use for reference came to the conclusion that the 1950 dated manual, at least for the back gears, was the closest one to how the majority of them were assembled. I redrew a few parts so that they actually looked like they would fit where he said that they had to go. And to the best of my knowledge, the 1950 version that is in Downloads and in Files on the A-C Group on groups.io is the nearest to being like the majority of actual 618's and 101.21400's, and excepting the headstock. spindle and spindle bearings, and countershaft bracket, 101.07301's.
The 1976 version introduces another washer, 932-004 (2 req'd but only one shown), there is only one M6-253 Collar drawn like it fits the shaft and not the eccentrics, and the M6-255 (only one shown) is drawn as though it fits over the left eccentric.