With reference to RogerSB's message above... The 'Lucas' brushes and pickups supplied by Wassell are usually OK. The black lines are caused by loose residue on the brushes which soon wears off. I always rub them on some very fine emery before using them and I have never had a problem.
I'm glad you mentioned that Andrew. I knew that, but maybe some didn't know.
(Edit) Here's another example:-
Look at the photo carefully and you will see that the Lucas face has actually been overprinted on one that originally was printed Royal Enfield. My camera showed it up as it's not visible with the naked eye. It puzzled me at first and then it dawned on me and I went looking and came across this horrible cheapy one for under £8.00 which shows the exact design that is under-printed on the Lucas branded one
.
It was returned to the seller.
(Edit - again): Maybe all Lucas branded components we buy are not the same