You can replace the harmonic balancer but make sure it is the same diameter or it could hit the timing indicator on the timing chain cover. Some of them had a the indicator that was held on with bolts and it can be changed if you go to a larger one. You also want to make sure the key is in the same place in relationship to the timing marks.
It is not uncommon for a balancer to wobble because some people might have given it a blow trying to knock it on. There is a rubber insulator that the outside ring is pressed on to. Sometimes they might just go bad and wobble for no apparent reason.
I have also seen them wobble from being in an accident and the front of the crank was bent, hope this is not the case with you.