[Thomas]

Ah, ok, I get it. I just checked everything again. For now the interior is clean but I will observe it. Thanks for your support.
Best, Thomas

[Greybeard]

By 'collar', I mean the wide band that covers the brush/bearing carrier between the dynamo body and the end cap, Thomas.
Removing it will give you easier access to get in to clean it. It fits in only one location as there is a notch in the edge nearest to the dynamo and a small peg on the dynamo body. That ensures that the clamping screw doesn't make contact with any of the components inside.
You may find it easier to refit the end cap before replacing the band as it then has something to help locate it.

Steve

[Thomas]

Hi Steve,

it seems to be a bush indeed and the felt washer is reasonably soaked with oil. I just cleaned the interior with brake cleaner. What exactly do you mean with "collar"?

Thomas

[Greybeard]

I think it's a fairly safe bet that it will be a plain bronze bush if it has the felt ring fitted . You may be able to see the bush if you gently move a little of the felt aside. You may well find that the felt ring will come away as it is often only held in place by the end cap If it's a shielded roller bearing you'll soon spot the bright silver coloured inner race around the armature shaft. It's just a question of keeping that felt moist with a drop of oil now and again rather than it being soaked and dripping.
There does appear to be a build up of carbon dust in there. Now you have the end-cap off I would be tempted to take the collar off too and give it a good clean and check that the brushes are moving freely in their holders and have plenty of life left in them. I've found that aerosol brake cleaner spray is pretty good at removing that sort of contamination and it evaporates off very quickly. With luck it will fend off the day when you need to strip the dynamo and give it a thorough overhaul.

Steve

[Thomas]

Thank you, Steve! Here is a pic of the interior. I found a felt ring and I am not sure if this is a plain bush bearing...
Cheers, Thomas

[Greybeard]

Hello, Thomas.
It should be to allow you to oil the end of the armature shaft, but only if it's still a plain bush bearing - if you've not had a dynamo apart you'll find that the armature isn't in the centre of the casing but offset. I would take the cap off to make sure that the bearing/brush carrier hasn't been replaced with one that has a sealed ball bearing for the armature to run in and the earlier end cap has been fitted. You certainly don't want any excess oil anywhere near the brushes/commutator ring 

Steve

[Thomas]

Hi all, there is a hole on the left hand side of the dynamo. What is it for? Lubrication of the armature?
Cheers, Thomas