If you can live without the ability to set the starting voltage CV2 and the top speed CV5 then try Hornby R8249, though you'll no have sound. TTS decoders can work ok, but need a few CVs tweaking when used with motors that have large flywheels like the latest 56s. Assuming Legoman supplied an ESU V5 then along with Zimo you've tried two of the best decoders for motor control. Gaugemaster decoders were based on DCC Concepts, but the latest Ruby series are Digitrax based. Digitrax are American, nearly all decent American locos from the last 30+ years have similar mechanisms to the new 56.