Class I: Die being re-hubbed is rotated near the center of the die from the position it was in during the original Hubbing. Class II: Design features on the Die/Hub become distorted or miss-shaped during the annealing/tempering process causing the images to no longer align properly when being re-hubbed. Class III: Happens when working hubs with different designs features are used to Hub a Die. Class IV: Happens when a Die is moved off center in the Hubbing Press from the position it was in during the initial Hubbing. Class V: Happens when a Die is pivoted around a point near the rim during the rehubbing process. Class VI: Happens when a Hub is overused and the design features become thickened or flattened creating thick design features on the Working Dies. Class VII: Happens when a Die being Hubbed is impressed with a normal hub and a then re-hubbed using a hub that has had its features changed or removed. Class VIII: Happens when the top of a Die being Hubbed is not parallel to that of the Hub.