Years ago my stock small block balancer did that. I didn’t notice till I went to shoot the timing and could not find the timing mark with the timing light. After scratching my head a bit wondering what the heck, I noticed an unpainted section on the front of my balancer that was in the shape of my counter weight…the counter weight had spun about 170 degrees. I guess all those nitrous blasts finally tor that stock balancer a new one.