As title 
The Madass has had a gremlin for a few days and now won't play.
The load shedding relay (wired to earth through the starter as standard) had been doing 2 things: oscillating for a second after the bike fires up, before coming in as normal; and occasionally doing the same thing but for longer - maybe ten seconds or half a minute - whilst the bike is being ridden.

Bike has been starting without issues through this. Today it's decided not to - starter won't turn, and the LS relay won't come in, even before I press the starter button.

So, I stripped the starter, completely worn brush not properly contacting the com. All makes sense so far. However...

Do I just swap the starter (or brush if I can find one) because it's worn normally, or could this be a sticking starter clutch that's kept the starter spinning and worn the brush - would a spinning starter generate enough current to stop the LS relay working in this way? Stuck my finger in the hole as you do, and the starter clutch spins completely freely one way, and locks immediately in t'other, just like you'd want it to.

Votes for option 1 will be most welcome. Votes for option 2 will leave me unable to do the decorating as planned tomorrow, sigh.

How many miles on the starter motor?

No idea, can't remember where it came from. The other brush looks about half worn, everything else seems reasonable - bit of black dust, no sign of excessive wear, been catching fire - that sort of thing.

The flickering of the LS relay was at engine revs - is that back current? or is it the worn brush touching a high point on the com?

Hang on - still thinking this through, the LS relay normally comes in as soon as the starter button is released - all starters spin on for a second or so after release, so if they were capable of generating a beck current to hold the +ve terminal high and prevent the LS relay from coming in, then it'd be noticeable, wouldn't it?

Edit: A 'beck current' is the same as a back current, in my head at least.

Sounds like it needs a new set of brushes.

Okay cheers. Paintbrushes unfortunately.

Chattering load shed relay is your clue it aint the starter clutch.

That's good news.

Really does sound like a starter starter brush issue.

Brushes are easy to do on most Ks.....not sure how easy it is to get your starter out......

Chris, have you checked the rear wheel shim?

I have a selection of rear wheel shims, naturally they're the first thing I try with problems like this.

The second thing I tried was a new starter motor. Oddly enough that had far more effect. Problem solved, no relay misbehaviour. Good call guys, 'preciate your input. Seems I was overthinking things as usual.

Cheers

I savour a definitive fix. Goodonya.