Ah, this sounds like another Hornby DCC problem. A lot of the Hornby decoders seem to have problems with all DCC systems other than Hornbys own. I am pretty sure that your ECoS is absolutly fine, but the problem is with the decoder. I would suggest buying some TCS decoders (not much more than a tenner each but very well made) and trying them. You will have no similar problems! Hope this helps,
Rob