Main gear rocking on OWB

[Sharpedge]

With the main gear bolted to the shaft, the shaft pulled and the collar tight on the lower bearing I’m getting so much lateral play (rocking motion) on the OWB that a cycle of up and down flexing of the main gear is able to rotate the shaft by 5-10 degrees. The gear remains in the same place during this process. I’ve stripped it all down and it looks ok to me. I take it that the OWB is knackered and needs to be replaced. I’ve removed the blades and tail and spun the heli up, the main gear does not appear to flex but it’s not under any load. I’m sure that it will flex under pitch changes as I’ve found dry shavings where the gear has been contacting the motor cooling plates/fins. The shaft spins up fine and runs freely when motor is cut. Is it normal for the OWB to fail in this way?