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Got a very quick response from David @ synchro tech saying the synchro is actually worn out. There should me a 1 mm space in between synchro and the gear cone it sits on.
The blocking ring (brass part) should not mate flush with the gear surface. If it does, no friction will be transmitted to slow the gear down when the shift fork moves the collar over both parts, resulting in a clash between the gear and the blocking ring (grind).
The fit you have pictured is a completely unusable blocking ring. The last one appears near new. There is a gap specification for these two parts, and this gap might change slightly with aftermarket parts. Reference a service manual for the wear limits if you are not certain. 1mm is not an unreasonable new measurement.