2004 R1150 RT Starter repair

On my  2004 BMW R1150RT, the starter was weak and then it stopped working. I could hear the solenoid clicking but the starter would not turn the engine over.

I removed the side panel and starter (using long extensions and a wobbly socket).  I disassembled the starter motor. I had to drill out a couple of rivets and remove the brushes and end cap.

Upon opening I saw the problem.

The armature was grounding out on the dust cap.  You can see the armature windings ground down in the photo above. And in the photo below,  you can see the grease dust cap is burned in a ring where the armature grounded out.

My solution was quite simple.  I cleaned the planetary gears in solvent to remove the grease. I then used a dry powdered graphite lubricant on the planetary gears and reassembled the motor WITHOUT the dust cap (item in photo above).  It is just a grease cap and it is not required.

This is clearly a defective design by the manufacturer.  

After reassembly, the motor works fine.