At our train club we have several display layouts that run modern locomotives, i.e. with DC can motors. The locomotives get a good work out and are often run continuously for 4 hours. At times the boards have failed and we are left with a shelf queen. The most recent one was an inexpensive Lionel Thomas locomotive. The motor is fine, the board is not. I would like to convert this locomotive and others to one way forward with the addition of a simple full bridge rectifier. Perhaps some 2 motor locomotives would be converted in the future. Can someone suggest an amperage rating that would be suitable? Is 3 amp enough or should I go with something bigger? Thanks for your help.