Contrary to common opinion steel wires should only be degreased before mounting, but not sanded. This would cause running out-of-centre.
After the change steel drive wire you should not use the grubscrews anymore. The max. force originates each with starting (turning up the system), i.e. over a longer period the shaft leaves it's marks on the surfaces of the grubscrews. If these will be in use again tiny rolled-in grooves might be formed.
The drive wire is no longer held between the screws, a tail rotor failure has been caused.