I just recently got a Muratec MFX-1430 copier off a friend and the only way I can get it to print anything is if I use the bypass tray on the side. Anytime it tries to grab paper out of the cassette, it says open side cover and remove paper. There's no paper jam anywhere. Sometimes it works this way and other times it just gives me the alarm. The bypass tray works flawlessly every time.
I have experienced this issue a few times with various printers I have been asked to repair.
Often times I find that the roller is slightly ajar which does not allow it to get a solid grip on the paper. Other times it may be the rollers are too close and actually touch at one point and the unit does not feel a "pull" as it simply guides along the other roller.
Sadly printers are poorly designed in that they do not truly communicate their faults, errors, etc. in a way that would allow for better troubleshooting.
If you dont feel either of the above are the cause, you could try grabbing a copy of the driver/software disc for your machine at the official site here and look for Printer/Scanner Monitor when installing. This should provide better insight into what is happening.