Wd 40 is a dewatering fluid and does not contain sufficient low temperature volatile hydrocarbons to run an engine so you will do well to forget that misinformation and everything else on that persons page / post they are talking from their rear orriface .
Magnets do not need to be clean & shinny , if they did they would be painted so once again ignore that and everything else that came from the same source.
Agressive cleaning of magnets with powered wire brushes actually changes the structure on the surface and reduces the efficency of the magnet . It is only a problem with very old engines where the very thick rust bridges the space between the magnet & the coil effectively short circuiting them.
So starting with a new spark plug.
Tip a very small amount of fuel in the spark plug hole or spray a SAMLL shot of carb cleaner down the plug hole.
Pull the starter rope.
If the engine fires and runs for a second or two then the ignition is fine
Repeat with fuel through the carburettor
If the engine fires & runs for few seconds then the valve timing is OK
This leaves you with the carb & fuel tank
Pull the fuel line off the carb.
If you get a strong flow of fuel till the carb is empty then the last man standing is the carburettor
So take it off, take it apart & clean it
You will find detailed instruction on the
Outdoor Power Equipment site
If the engine is difficult to pull or the is very jerky then reset the valve lash
eThe most popular sites on You Tube & Face book are videos & photos of peoples cats.
That should go a long way to evaluating the interlect of the average poster there and the people who frequent such sites.
FOrums were invented for people who KNOW to share REAL INFORMATION .
The most common problem with push mower engines is a gummed up carb
The second most common fault is valve lash out of adjustment .