William. Make sure the air gap between the sprocket halves are equal. Try to use a thumb to hold down the sprocket half firmly on the sprocket carrier as you tighten the Center bolt. Make sure your sprocket half spans the split in the sprocket carrier and does not line up with it. Make sure your sprocket carrier is true as far as left to right runout. If not don’t throw it out have a friend with a lathe use a piece of an old 50mm axle and take a few thousandths off until true. If you don’t take the clutch apart to clean it , at least spray brake parts cleaner in the drum area (use the tube so you can direct it better) to remove the dust. When you’re done with the brake parts cleaner don’t forget to use some white lithium grease on the roller bearing. You really should do this before each session, but don’t go crazy with the white lithium grease, it only takes a little bit. Just two small squirts directed between the mount bolt and the drive sprocket. Make sure to use the tube that comes with the grease. We race the 401 also runs nice. Good luck.