Lucas DFL Dynamo

[akharding]

I have a Lucas DFL dynamo on my mag engined Chummy. The dynamo was rebuilt a few years ago and has not done a lot of hours since.
It regularly fails to charge but usually responds to having the commutator cleaned with switch cleaner - but only for a while. Before I do this the commutator has a black oily appearance.  Is this likely to be due to oil getting in at the drive end, over lubrication dating from the rebuild, or carbon coming from the brushes, -or something else?

 I am running it in 2 brush form with a solid state regulator, not that that would make any difference I guess.

T I A

[Jeff Blight]

Mine does the same I have come to the conclusion that it’s oil on brushes and com a quick blast of brake cleaner and it will charge for a while have lived with it for years as don’t use much in the dark

[Lance Sheldrick]

I also had this problem. I fitted a new felt seal and problem was solved.