Sounds like youve lost ground mate - tingles would suggest this.
Your Black wire from the cap would more than likely be the ground wire also.
Unplug your machine and follow ground through till you find the fault
What are the chances of a new capacitor fixing everything........I can only hope.
I don't think so - I'll have to check pictures of my Jacks Open, but EMs operated before Caps were introduced. There was a cap installed on a small board - but I'll have to check.
Gav is right - You have lost ground "somewhere".
What are you touching when you are "tingled" ?
Maybe try cleaning the connectors that go into the head with a wire brush and look for any wires on these connectors that may either be lose or broken.
