Hi Whittie, this fault is very common, cause a mass of weight locked in by a tiny little woodruff key, need to single keyway the crank snout, and there is a chance you may not even be able to get it of and if you do the damage to the crank wont enable you to get the new one on, the harmonic ballancer will be ok , the drive pulley that it bolts too will be damage, this happened to me i couldnt get the pulley off i bent a pro lisle ballancer pulley and 6 high tensile cap bolts trying, so i figure it aint coming off in a hurry so i pumped some loc tite in the front of the snout and tightened the bolt with impact gun , and has been the same for years , if you need a new drive pulley give Rob at robco a call 03 97751413 . Daniel.