So the other day I tightened up my chain (pulled back the rear axle). I gave it about 1/2-1 inch free play. Now when I slow down I hear a scraping noise. My assumption is that the further you pull the rear axle back, the lesser the angle to the drive cog, and that now when I slow down, the slack is grouping up and scraping just under the chain part. See attachment for a better explanation. I went to my local mechanic and he said I will need new cogs, and chain ($600 fitted). Just wondering - how hard is this job to do? And what parts will I need. Bike is Suzuki Across GSX250F 1999 Edit: The bike does make a clicking sound when rolling in neutral.