Hey there ,
These engines rarely give any ignition problems , the most common being the kill switch pins.
the screw in the spark plug lead is how they are from new , stupid question are you attempting to test the coil unbolted ? when refitting the best way to gap the coil to the flywheel is a business card between the two.
another thing may be that the screw is no longer in contact with the copper in the plug lead.
it is possible that the ignition module is to blame make sure that the rivet holding it to the block isn't loose it earths through that connection.
the cylinder head you have the spark plug resting on is fine for checking spark.
cheers ,tomo
