A quick fix for for 'indexing' headsets is to replace the caged ball bearings with loose ball bearings. Typically, the change in in ball to ball spacing prevents them from aligning with the pits in the races. However, that does not address the root cause. Conventional thinking in that the problem stems from a loose headset but Brandt contends it's lubrication failure.

Misaligned races are easy to identify from the wear pattern. The width of the wear track changes gradually from narrow on one side to wider on the other.

I don't know what VO's thread designation system was/is, but F can designate Italian threading, as F = fili, which means threads. It's best to check for an actual numerical designation.