There is a device that slides back and forth and acts like a window cleaners on the printhead.When this printer is off the printer head can be tilt sidewise freely by hand which allow easy access to the mentioned cleaner sponge tab located below the head in its docking position. The mechanism that drives the sliding squeegie relies on a spring for it to return. The spring sometimes isn't strong enough to over come the gluey ink and so the whole thing jammed up which is probably what the code means - jammed mechanism. Try cleaning this mechanism and carefully moving it.
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