It won't spark! Now what? (missed a bit)

[buzzawak]

The spark plug cap has a small spring, resistor and the brass screw (the brass bit is the part that connects to the spark plug top thread.
This bit can become loose (it screws in) and results in burning the top of the contact, spring or resistor.

[DonTZ125]

Added - thanks!

[ramster]

The spark plug cap has a small spring, resistor and the brass screw (the brass bit is the part that connects to the spark plug top thread.
This bit can become loose (it screws in) and results in burning the top of the contact, spring or resistor.

You could even dump the resistor's then replace them with short lengths of 3mm welding rod coated in dialectic grease. Then there's the White inline connector from the Start Relay to the main fuse, it can become corroded