Hi I have a problem with a Heljan class 37 O gauge DDC sound fitted loco. when you go to full power the loco moves a few feet the locks up, the sound stop but the lights stay on. the controller has no effect on the loco. the power has to be removed from the track before the loco will restart. this problem has now happens with two locos both fitted with Loksound v5 xl decoders, they are bifs 37/4 wheel slip sound files. Bif kindly sent the files for me to re-blow them but it has not solved the problem. anyone out there had a similar problem? any help appreciated.