Cause of Son 28 dynamo hub squeak?

[321up]

This is the new design on Son 28.  It sounds like it could be a cartridge bearing intermittently squeaking, but I wonder if it could be another cause?  Perhaps a small bit of grit in a seal?  Thus far it turns freely without any slack in the bearings.  The issue is if it is safe to ignore for now or if it could fail imminently?  Thanks.

[aidan.f]

I  have read about internal corrosion  - the internal  clearances are tight between rotor and stator. having said that later models all have pressure relief to ventilate the innards.
I would ride on, I do not think it will break and if it gets worse SON will repair.

SON 28 klassik (K-No. 179) and SON 20 (K-No. 165) may stay in the whole wheel for service. All other models (e.g. SON 28 new or SONdelux) have to be disassembled for repair. In case of a warranty claim, this will be free of charge.
5 years warranty/ guarantee given from date of purchase. Do enclose a copy of your receipt.
For customers from abroad special conditions apply; please inquire in advance.

http://www.nabendynamo.de/service/reparatur_en.html

[Blodwyn Pig]

give it some cheese