You seem to be missing the point, the balancer does not slip all the time, it has slipped in the past and now the mark is off. Set no1 piston to tdc and make a mark on the balancer at 0° or tdc. Or just verify that the mark is still aligned with tdc on the engine. Takes 5minutes to check and then you know whats going on with the timing.
Otherwise, just connect the timinglight to no1 and turn the distributor, but that might **** up the motor.
Slipped balancers don't just slip to 180 degrees and stay there. Back to school, sonny....