My barrel has either a sticky or broken tumbler so I've had to remove it. I thought it might help someone else too.
You'll need to remove both column covers and speedo cluster surround first. Then remove steering wheel. Once the wheel is off you'll see some screws holding the combination switch on, undo these and swing that off the column. On the bottom end of the barrel is the switch, held on by one screw. Remove the screw and swing the switch out the way

On top of the ignition barrel is two shear bolts, these hold the barrel onto the column

They need to be removed with a hammer and chisel (or punch).

Once the shear bolts are undone you can remove the barrel assy from the column.

Once I've worked out how to remove the barrel guts I'll add that in