Hi,
This sounds very similar to a problem that I've been having intermittently. Here is a list of fault codes for the ZWD1470 (I assume the same codes as the 1471 that I have):
http://www.fixya.com/support/t146599-error_codes
You find the code by holding the start/pause and reset buttons simultaneously, once the machine has stopped and the start/pause led is flashing.
Should give you a better clue as to what needs replacing.
Bob Humphreys, August 2010