ballaster question
If it gets wet it could be failing -- these things run HOT and a sudden dash of rain might just break them
You might have a mismatched coil--and it is drawing too much current
Where did you get them? Nowadays, QUALITY seems to be a real issue with parts. I'd try a good name brand part, as opposed to some of the "big box" stores
For the record, I've never heard it called a "ballaster" It's a "ballast" or "ignition resistor" or "coil resistor."