"David, the "black box"
"David, the "black box" is a powerpack - fairly easy to swap out, and yes, the description of your issue tends to indicate that as a "potential problem" - but it could also be the stator itself (or a couple of other things).
Some of these are not the cheapest items. So I would make sure it is the problem before you just go about "swapping" parts trying to find the issue.
You can check most of your ignition components with a multi-meter and a good service or repair manual.
If you don't want to go that route (or don't feel comfortable doing it), kick in for an hours labour and have a shop look at it for you. That could well be cheaper in the long run...."