Spark Plug/Suppressor Cap for KX500 - Answers Appreciated

[streetsleeper]

I had my KX500 running, but this was short lived. There could be several things electrical wrong with the bike, but one thing I suspect is that the plug cap is shot (or might you suggest otherwise?). I used to have a nice, big, fat blue spark, but now I have to shove a tight-fitting nail up inside the cap to get a spark big enough to jump from nail to cylinder head nut. I'm dead sure she has the original cap fitted, so what I'd like to know is this: is the HT lead made of copper and tin plate or is it one of those carbon resistor types. I'm not able to unscrew the HT lead at either end so want to be sure which plug cap to buy when I come to cut it. Any suggestions, recommendations, dos or don'ts, or any other reason it's not doing its job? Any photos would also be helpful.
Thanks in anticipation.

[streetsleeper]

I've been thinking about this and the problem is much more likely to lie in either the coil or the CDI. I can't afford to buy new OEM parts, and there's nothing available second hand here in Mexico. What I've decided to do is get hold of an OHM meter and follow the instructions that sandblaster gives in his topic under KX500 Original called: Having electrical problems on your K5?
Apparently there was more than one part to this topic so if sandblaster or anyone else could point out where, that'd be great. I have a whole host of questions to ask about my KX but I'm not one to give up. Furthermore I need transport. Although the bike is still in its original trim there is special dispensation for bikes over 30 years old in Mexico (it's an 87 with cylinder from an 88) so I should be able to use it on the road. Nothing is easy but perseverance and patience should pay off.