Hello all,

Final update, now that I have opened, cleaned and replaced the balls in
my front hub dynamo that was making cracking or clicking noises.

The hub dynamo was a Shimano DH-3N31. I was able to open it with no
real issue, and without breaking the phase wire. That wire comes out of
the dynamo through a groove in the axle, and is routed to the outlet
connector through a contraption that is built around some kind of special
washer that fits the groove, so it cannot rotate, reducing the risk of
breaking the wire that way.

What was very wrong, is that the power-side locknut was loose, allowing
the cone to be loose too, which would explain the noise I was noticing,
and to eventually tighten itself, causing the high drag that eventually
appeared.

I also noticed that side of the dynamo was distorted, like part of it
was pushed inside by less than one millimetre. I supposed I once rolled on
something that got caught between the fork and hub, damaging it and
loosening the locknut. Anyway, the dynamo is not broken and appears to
function correctly, so I will keep using if for now, monitoring it
closely.

I found nothing wrong with the cones, balls and cups, but I replaces the
balls anyway, and ajusted everything back. It is working correctly now.
:-)

--
Tanguy