The spring most people talk about is the larger one that goes in the large end of the plug cap...The little spring inside the silicone part of the cap doesn't usually come out and if you look at the cutaway view you can see the end of the resistor just goes through the side of the spring and doesn't always contact it...The spark jumps from the end of the resistor to the spring.....I don't know if the little spring even comes out....
The metal shield on the cap and wire stops RF....If the cap isn't all the way down on the plug it could cause interference...I have taken some of the factory inst alled caps off the wire and the resistor wasn't t here, just a short piece of wire to go into the spring...Works well either way...
No one has ever been able to tell me why a resistor is even needed in a completely shielded system...All mag Zenoahs and Quadra engines use a rubber cap with no shield....They NEED a resistor plug....There is no short thread resistor cap available...None of my Zenoah engines in any of my planes ever used a shielded cap...None of our GT80s in the race planes use shielded caps...