MF12 square baler needle timming

I've just bought a MF12 and was trying to get the timing right and I've noticed that the needle arm drive is lagging by approx 1/8 of a turn when the knotted clutch is disengaged. The stop dog is in contact with the metering pivot assembly. All roll pins and keys appear to be ok. Does anybody have an idea on what is wrong?

MF12 square baler needle timming