This is very common. The printers are very low quality in this model. If you started losing parts of the printing, then lost all print, the printer is probably faulty and needs replacing. luckily, the printer is very cheap as far as cash register printers go. Once it has been replaced, make sure you have the receipt set to off mode, so you only issue receipts when asked. this will make the printer last a lot longer.
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If anyone needs more information, the casio TE-M80 cash register manual is here:
http://the-checkout-tech.com/manuals/cashregisters/Casio_TE-M80_users_and_programming_manual.html
Registerman
March 2011