By the way, I have many open frame motors running on my layout exclusiively with DCC. I have found they draw in the neighborhood of 2 amps in most cases, some more, some less. I have programmed my Digitrax breakers to 6 amps since I have an 8 amp digitrax command station.
Most DCC systems are alt least 5 amps. So you could try setting your breakers to 3 amps and see what happens.