Panasonic KX-FB423CN Manual page 286

6.5.4.11. AN ABNORMAL IMAGE IS PRINTED
* We recommend making a copy of the Fig. b document in NO DOCUMENT FEED, DOCUMENT JAM and MULTIPLE
DOCUMENT FEED(P.76) and using it.
CROSS REFERENCE:
HOW TO REMOVE THE THERMAL HEAD (P.34)
TEST FUNCTIONS (P.57)
ANALOG BOARD SECTION (P.103)
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KX-FB423CN