I've got an interesting scenario, fitted a Bachmann 21 pin decoder to my GBRf Class 73, resoldered the wires for correct directional running, tested with my Dynamis and all ok. Run in on DC all seems ok.
Set it to run on the layout and it will not respond, sets off at a crawl but is uncontrollable. I use a basic EZ controller on the layout, similar problem I had with my Windhoff MPV unit that wouldn't respond, and ended up fitting a Sapphire Decoder which resolved it.
Just wondered whether anyone else had had a similar problem with their loco.
http://www.rmweb.co.uk/community/index.php?/topic/55835-a-problem-with-my-class-350/?hl=sapphire&do=findComment&comment=680845