Picked up a used BR 430 - wont start.

[Hammermechanicman]

Yeah, was born in 70.

Kids now a days.

 

[bertsmobile1]

Depends upon the engine & the type of plug lead
The worst are the graphite leads because the graphite dust gets shaken by engine vibrations till you get sections where there is none
Solid copper wires tend to only leak at the boots particularly if the engine is old and has a bit of oil fume deposited on everything
Spiral wound leads never fail which is why high end vehicles use them plus a lot of F1 engines.
The fun is when they hold tight at idle then arc every where at high revs

 

[Fish]

I've never heard of spark leakage before.

Leaking starts to be a problem when you hit 50 years old or so.
It "Depends"...........