Oki PT340 User Manual page 40

(6) Open the top cover and remove the jammed paper while holding the
printer steady.
Caution: When removing paper, remove the paper slowly without
pulling it forcibly.
Caution: As the thermal head may be damaged by static electricity, do
not touch the thermal head. Also, do not touch the thermal
head as it may still be hot after printing.
(7) Set the paper correctly and carefully close the top cover.
Caution: Set the paper correctly. Closing the top cover while the paper
is skewed may cause a paper jam or messy printing.
Caution: When closing the top cover, close it securely by pressing
around the central position until you hear a clicking sound. If
the cover has not locked into place, the printer may not
function.
(8) Turn on the power switch. Also, at this time confirm that the ERROR lamp
has turned off.
Caution: As printing data cannot be received while the ERROR lamp is
on, firmly close the top cover.
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