As you may have guessed by now, that model AmpTraXX is fairly old and now out of production. In fact, the reason we had to stop making it is because the power supply manufacturer went out of business. We were never able to find a suitable replacement with the same form factor and specifications. Over the years, we have kept looking for any supply that could do the job, in an attempt to help existing users, even if it had to be external to the AmpTraXX.
The best and safest option we've found so far is the model train power supply referenced below. Several other AmpTraXX customers have used it with success.
https://www.digitrax.com/products/power-supplies/ps2012e/