So the procedure to carry out an ignition switch swap is described in the WIKI and no doubt elsewhere in the forum and archive but since I took a load of photos while I did it I thought I might as well post them up.
First up remove the horn button and disconnect the horn connections.
Undo the nut holding the steering wheel on.
Mark the shaft and steering wheel with a marker so that you can line up the steering wheel when you put it back on.
Remove the steering wheel, disconnect all the cable connectors and undo the three screws (no need to take them all the way out) and remove the switch levers.
There is a bolt that need to be removed and it may well be a shear bolt (for security) and will need to be undone by using a chisel and hammer and hitting it on the edge to unscrew it. As you can see ours has been off before and has been replaced with an 8mm hex bolt. I think you can do the same.
Stick the keys in the ignition and turn them enough to take the steering lock off and use a mallet to gently tap the whole assembly up and off the shaft.
This little black bit fits quite tight in the shaft and is the reason for the need of a mallet, it is the bit that cancels the indicators when you turn the wheel. take care not to damage it when you take it off. gentle taps with the mallet is all that is needed.
You'll end up with the ignition assembly in your hand
Turn the assembly upside down and you'll see the screw you need to undo to take the switch out
Remove the old switch and put the replacement one in. (£6 from brickwerks)
Now just reassemble it in the opposite of disassembly and job done. This is an easy job that shouldn't too long and from what I can gather is something you will most likely end up having to do as the ignition does not run through a relay and the high current that runs through the switch eventually wears out the contacts through a bit of arcing.
