If you think the balancer has moved, i'd just replace it.
TDC can be a pain to find with the engine in the car. You need a positive stop to screw into the spark plug hole. Rotate the engine by hand until it comes up against the stop and mark the balancer at the timing pointer. Rotate the engine the other way until it comes up against the stop and mark the balancer again. Then measure half way between the 2 scribe marks and that is TDC.