I hate to say this but transformers don't output DC current, power supplies do.
If you lost a power supply then I would say something failed in the Emg light, most have voltage regulators and charging circuits that could have went bad also, like said, find a 12-15 DC volt wall wart that outputs at lease 1.5 amps, and make sure you get the polarity correct, and try it, I have a bunch of them I have picked up over the years at garage sales, I keep them around just for things like this.