into mortise 42 in the cover 14 the lower tenon 40 fits into a similar mortise not shown in the housing 12 the used ribbon 18 is guided to the take up spool 15 through two meshing gears 37 and 37 39 gear 37 mates with an external gear 37 39 to provide positive ribbon drive these meshing gears positively capture the used ribbon 18 thus causing the ribbon 18 to be positively advanced without slippage along its passage through the cassette 10 to the take up spool 15 a felt wiper pad 27 fig2 is disposed within the slots of abutments 28 and 29 the advancing print ribbon 18 is guided past the wiper pad 27 in order to remove any extraneous ink particles from the ribbon 18 prior to its transit past print window 11 now referring also to fig4 the path of travel of the ribbon 18 is described in detail the ribbon 18 first winds off the supply roll 16 in a clockwise direction step 100 the ribbon next moves around the lower right roller 52 rotatively connected to the lower right pivot pin 50 then the ribbon 18 moves towards the upper right roller 54 rotatively connected to the upper right support shaft 56 step 102 next the ribbon 18 moves past the print window 11 step 104 after passing across the print window 11 the ribbon 18 moves around the upper left roller 60 rotatively connected to the upper left support shaft 58 down past the gear 37 and along the front surface 68 of the chevron 5 step 106 now the ribbon 18 moves around the lower diagonal surface 32 to the back surface 64 until it reaches the upper diagonal surface 22 step 108 and then proceeds up.