18-04-18, 10:52 PM
I had a really minor 'knock' on mine. MOT guy couldn't diagnose and said too minor for an advisory. I thought it could be any of the above, so did a complete fork service (seals and oil), (check the cap heads are tight on the bottom end of the forks). New and correctly adjusted head bearings sorted it! Yours might just need tightening.
-suck-squeeze-bang-blow-