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head badge is something we have not asked about
expect you would have examined head tube interior for any sign of fastener holes being filled in
still think no-slide bit the most helpful clue...
a good many very knowledgeable readers have probably looked at the thread and thus far no one hath writ of recognising this feature
should your explorations reach a point where you have an identity candidate one construction detail which might be helpful is the presence/absence of pinning
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Last edited by juvela; 06-02-19 at 07:07 AM.
Reason: addition