Wondering about  an  "upgrade"from a spur to rim  on a ea4300 when I replace the sprocket?   Clutch Drum Cpl Dcs4630/5030/ 181223200 from Spare Parts World WWW.SPAREPARTSWORLD.CO.UK     Sounds like a shim is needed?   Dolmar 421 sprocket clutch drum options?? | Arboristsite.com WWW.ARBORISTSITE.COM Yesterday I bought a used 421 for what initially looked to be a good price when it fired right up. I k