Hello Fergus

A warm welcome to these forums.
There should be no problem here, and we're sure we can help.

Parts could be available as easy as here:-
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=69724

New parts could be available here:-
http://www.villiersparts.co.uk/ignition.html

Please feel free to post photos for positive identification HERE.

The AV is a great AUS reel mower.

Hope this helps.
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Jack