Starter motor rebuild

[Spondonrider]

I have a couple of bad starter motors here, one on the bench and one in my Spondon framed bike. Both have bad spots that the motor wont operate from but if I rotate the motor a slight bit then it works fine, until it stops on that bad spot again. I have dissembled the one loose motor and other than dirt it looks ok. Is this "bad spot" caused by a dirty commutator? I've cleaned it with a scotch brite pad and it looks pretty good. How about the brushes? They look ok to me, just worn to fit the commutator but plenty of brush left and good spring tension. What do you all think?

 

[RCGBOB44]

Clean the lot and replace the carbob brushes.

 

[Simonr501]

I took a motor into an automotive electrical shop a while ago as it had the same symptoms.

I blathered on about changing brushes and all that but they put it onto their rig with flashing lights and the thing that goes 'ping',  turned the motor and the little light went out in one position -  knackered slip ring!!!!
Something to consider but it's probably worth changing the brushes anyway, since that is so much easier.

 

[dja981]

Shouldn't the brushes be more carbon coloured than copper coloured?

                                                                        Dave