It had one too many bearings on one side. Hence the very odd wear pattern on the cone. BTW, the customer was really impressed that I found the problem with his wheel.

I'm working at Frank's Spoke'n'Wheel in Sudbury. Love it. All the cool bike tools from the 70s can be found hiding somewhere in the shop. Today I needed to replace an axle and cones, and we had them. There are even 10-20 year old brand new bikes and frames sitting in the attic - Bianchis, Bridgestones. I've got my eye on the 52 cm Bridgestone MB-3 from 1994.