The original control system was removed from the Loco (failed, scavenged for another loco, etc.).this is great information many thanks.
I used a gaugemaster controller (DC) and just touched the centre pickup and a wheel and motor ran.
there is a speaker which i removed from the base but it was not connected to anything.
At the least, you need a bridge rectifier to run the Loco's DC motors on classic O-Gauge AC transformers (Forward Only - $10). A step up would be a reverse module that would provide DC to the motors and offer reverse capability with minimal sound (Horn & Bell, $60+). After that there's several options to add sophisticated control systems, enhance sound, "cruise control", etc. ($100s+)