I think when I need one I will buy a rebuilt or remanufactured one, or send mine to somebody to get it rebuilt. I'm just tired of Chinese stuff that works for a little while then falls apart.
I don't know if these are the right people, but I bookmarked them a while back and they may be worth a call.
http://philbingroup.com/rebuilt/distributors.htm
Their website is kind of cruddy and has broken links, but I see they have a phone number to call. They don't seem to have crazy prices. I'm not endorsing them, just suggesting you be our test animal and let us know how it goes. :-)
The problem with your HEI may be in the wiring that powers it. Maybe you have a corroded connection or wire, or maybe the coil is giving up.