I don't know about your coil, but your batteries don't sound entirely safe at this point. A number of things happen as batteries age, and some of them can put you at risk of catastrophic failure (i.e. boom!). As you've mentioned sourcing from Amazon and Ebay I'll just note that those aren't the places to get batteries. Counterfeits abound and can be very dangerous. Besides, they don't tend to be much more expensive at reliable vendors. If you're interested in replacement batteries, I'll refer you to Mooch's chart. His recommended batteries are here. There's also a list of reliable vendors in the blue row of the chart.
