I´ve just got a new Porter 0-4-2 DCC with Tsunami Sound Decoder. The engine runs smooth. But if I change the direction from forward to backward or the other way the locomotive doesn´t move until the throttle is on 12th speed step. Strangely the exhaust chuff starts at the first speed step. I´ve already "played" with the starting voltage, the accelertion rate, the speed tabel and the forward and backward trims. Any suggestions? Thanks for your help.