Sounds like a problem with the printer. Have you tried the files on the supplied SD card? These are simple to print and will prove if there is an issue.

TBH, it's not an issue I have ever had, but that's not to say it's not a problem with the printer.

Please use this link: http://www.dropbox.com/s/p8osla4lmga...Plane.x3g?dl=0 to download a simple file that I know will print on a CTC without issue. It uses the right hand extruder and should be OK for either PLA or ABS.