Your problem is your sensors are dirty. Pull it apart remove the bottom part of the unit there is a tab on the botton to release the unit from the validator case then it slided out to you there are two little holes there blow them out then clean the little glass spots between the rollors/ belts put it back togeather and it should work again. I have that issue all the time because I have 4 machines place at one location in a dusty enviroment. I stay ahead of it most of the time by cleaning the acceptors each time I service the machines.
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