whining noise under heavy aceleration

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at the start when i accelerated hard i heard a whine sounded like maybe a bearing noise. when i dropped the clutch and throttled back the noise was still there but got slower and stopped before i did. i could then acelerate again normally with no noise it looks to be geting worse as time goes by.

i have noticed that the started was getting sluggish so i have pulled it out and found worn brushes but was wondering if the bike is not charging as it should.

So do i have to take the engine out and work through it or does any one think it is some thing i can get to without going the whole way? :|