I bought a used Modfactor and registered it with no problem just by entering it's serial number, but perhaps I was lucky in that the original owner had not actually registered it.
Perhaps yours has been previously registered and Eventide's computer program won't let it be registered to more than one owner, but you would hope that contacting Eventide about this would sort it out (they could email the registered owner for a start).
It's irresponsible of the previous owner(s) not to consider this, but hey, it's a jungle.
Good luck.
