750 starter brushes

OK, I had some starter troubles in the past with it not turning over. I was able to solve these problems by just cleaning out the starter and re-lubing everything. It recently started not working again so I took it off and gave it another cleaning. This time it didn't help. The gears and everything spin very smoothly so I tried jumping it off my car battery but couldn't get the starter to turn over. Looking at the brushes in the starter I noticed that one was quite a bit shorter than the other (one on the left)
I am assuming this is the culprit as I heard that starters are really sensative to the brush length. What do you guys think?

 

I've had starter issues AFTER I replaced the brushes. It all got down to making sure the brush plate goes back into the housing in EXACTLY the right place. Mine was 180deg out I think causing it to spin BACKWARD!!??

After cleaning the armature and especially the commutator put it all back into position using the exploded diagram in the Haynes manual as your guide to fit it in exactly the right postition - I found the the brush plate doesn't have an exact cut-out type fit and can be placed in a number of positions so getting it right is important, plus the reconnection to the cables needless to say.

So long as the brushes contact the commutator it should work OK, even if the brushes are worn. The location of the brush plate is absolutely important to it a) spinning, and b) spinning in the right direction! Might be worth looking at the starter motor repair kit available on ebay as well.

 

The left one looks short. Minimum length is 8.5mm. Replacement brushes are available at oldbikebarn.com for about $20 USD.
One good and quick check is that the metal piece that the brush slides through is 9.7mm long. Push the brush back until the end is flush with the back of the metal piece. If is is shorter than the metal piece then it is near minimum length.