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its always good to begin at the root

suggest to face head tube & mill fork crown race seat

headset does not "look" like a Stronglight model P3 or V4

looks more like something from Etablissements Gourgaud (LIGHTRACE brand)

if the lockring is marked Stronglight it may be that the set was put together from pieces

one thing encountered occasionally is a cycle whose headset has been assembled from miscellaneous bits which do not always work well together

suspect source of looseness may be fit of lower head cup in head tube and/or fit of fork crown race - this is a fit which needs to be tighter than interference; it needs to be press

if one of these fittings in not tight enough shimming may be in order

if using retainers try changing to loose ball - these will give longer life in terms of brinelling resistance


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