If the elastomer is sliping between the inner and outer ring it will probably slip some more.If it's an old original harmonic balancer ,they do go bad. I'm using an oem harmonic balancer but it is in good shape.. The key can also shear. Have you checked that?George at Gueeesford said the key was just for locating ,the press fit and the torque on the bolt are actually keeping the harmonic balancer in place . The torque on the ARP bolt I installed is quite a bit more than oem.If the harmonic balancer isn't timed correct, keeps changing referense marks what good is it anyway? sounds like it is just keeping the
oil in the timing cover.