The easiest way is to buy one on eBay. I bought one and found my problem was a spring broken in the ignition switch, behind the barrel. To remove the barrel I had to poke a small screwdriver in a hole beneath the metal casing. You have to remove the plastic shroud first.
The current price is $14.95 + $8 postage. You may be able to get express postage.
https://www.ebay.com.au/itm/NEW-IGNI...8AAOSwI8laMlam