Check the printer for paper or ink ribbon jams. Once you have cleared the problem, set the key to REG mode and turn the machine off at the wall, then back on. If the printer error returns immediately, you will need to have thee printer repaired.
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If anyone needs Sharp ER-A570 manuals, they are all here:
http://the-checkout-tech.com/manuals/cashregisters/Sharp8.php
Registerman, February 2013
