On my 89 240 GL, the  original crankshaft pulley (harmonic balancer)
failed, the rubber bonding between the inner and outer halves broke and
disintegrated. The outer half ended up cocked at about a 25 deg. angle, and
had ground away one side of the timing belt cover. And of course it ws no
longer turning anything, as it had completely separated from the inner half
of the pulley.  I replaced it with a junkyard part for only $60. Highway
robbery for a part that is15 years old, but better than the alternative. The
very cheapest price for a new one was $120, and that being more than I could
afford, I opted to take a chance on the used part.
     Finally got the right alternator belt, started the car up, and all is
working, but the replacement crank pulley is wobbling  severely. It is
cocked or out-of-balance.  I did notice before installing it that there were
three shallow 3/8 in. holes drilled close together on the outside
circumference, not far from the rim. So I know that this balancer was
balanced in the past.  So what to do at this point? It is so wobbly that the
rubber bond is going to fail (again!) from the rapid tightening/loosening of
the belts as it turns....and man, are those belts jumping! I cannot drive it
like that.
I suppose I should try removing/reinstalling the crank pulley once, to see
if maybe for some reason it didn't seat flush. If I still have the same
problem, then do I need to have an automotive machine shop re-balance it
somehow? Can this be done when there are are already three holes drilled in
it?
    But it looks to me more like it has a  wobble from not being in proper
axial (?) alignment with the shaft, rather than just being an unbalanced
vibration. If that is what it is, can a machine shop grind the surface that
mates with the crankshaft end so that the wobble is eliminated?
  What are the odds of a NEW crankshaft pully fixing this problem?   It
might not, I guess, because the way the crank pulley failed it might have
BENT the crankshaft end due to the way the loose outer part of the pulley
got jammed up....maybe?
   Also, is that the actual end of the crankshaft that the crank pulley is
attached to, or not? Because if it is the actual end of the crankshaft
pulley that is bent, then I am really screwed, as they say.