I was a bit concerned how rusty the harmonic balancer / vibration damper was and the rubber bonding looked dry and cracked which may be the first signs of it failing.
I ordered a new harmonic balancer from Rockauto based in the USA which only took 3 days to arrive. Had to buy a removal tool as well.
A means of holding the pulley whilst trying to remove the pulley bolt is required – I used a length of angle iron.
The new pulley fitted quite easily once the woodruff key was aligned correctly. I turned the crank to ensure the key was located on the upper surface to ensure it did not drop out of its slot in the crankshaft prior to removing the old pulley. It is also important to follow the tightening sequence of the crankshaft pulley bolt.
MG ZT info mods and maintenance 