Ah the good old void bush, Right bar stewards to change.
As said cut the old ones out and clean the hole out with a bit of emery tape.
If you go down the sockets and washers make sure you get them dead straight cause if the bush twists as you start your in a right pickle.
Oh a night in the freezer for the new bushs helps a bit as does a smear of copper slip.
Good Luck.