I have recently been ' doing ' a Shanks Wren. During the course of dismantling to thoroughly clean, I noticed that the holes in the cylinder pinions were off centre. Presumably this isn't deliberate and can't be wear so I put it down to the foibles of mass production. It doesn't seem to affect the performance of the machine, which is actually very good. Perhaps this is an indication of the general decline that Shanks were suffering when this machine was produced - early/mid 1950's.
I've not particularly noticed this with other machines to the same extent before but I'll now be on the lookout.