Fleischmann factory installed decoders

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Received a gift of a loco (Fleischmann) with a factory installed decoder. Can't get the lights to respond properly, either I get nothing or all on with no directional control. I believe the issue may be with the CV settings. Using a Digitrax Superchief so I believe there is an issue with a conflict of the decoder being factory set for 14 step operation and the command station being 28/128, but I can't work out what the decoder CV settings should be to resolve the light control. Any experience or solutions out there?

Thanks

Phil