On my 83 XL600R I've noticed that the spark plug cap doesnt "snap" onto the spark plug. I thought maybe the spark plug cap was designed for a full size spark plug terminal instead of the small threaded one, so i tried a regular plug, and the cap wont fit on at all. Seems like the cap(coil end) is either extremely worn out somehow, or its designed for some specialty spark plug that ive never seen before. I'm guessing i should replace the cap, but with what? Can i just do a new wire/cap? Or do I have to replace the whole coil?