I purchased a spectrum dash 8-40 cw dcc ready. I have not installed a decoder yet. I placed it on my dcc layout and it goes forward and then stops goes forward and then stops and keeps repeating this. I have two other non dcc spectrum locomotives that I run on this same track and they operate just fine. I placed it on a small DC track and it operates just fine. Anybody have any ideas where to begin to look for problem? Any help would be appreciated. Thanks