is the gate actuating? the soleniod is inside the adu, it pushes a white arm up ( which you should see on the adu to the left, on top ) , when those machines came out we had quite a few where that white arm wasn't pushing high enough to operate the connecting arm which then in turn operated the gate, so we used to glue a piece of feed tyre on top of the white arm.
another thing that caused jams on these machines was the metal plate on the u-turn ( just after the fuser unit ) , they bought out a modified plate which we call the " cheese grater " , it's drilled full of tiny holes, the reason being that moisture comes out of the paper as it exits the fuser & it would soak the u-turn plate, then the paper stuck to the plate.
also the exit actuator bracket of the machines would get bent, it can be in a position where it still works on single sided, but because of the angle of paper when duplexing, it causes a problem.
finally, if the dampers are shot ( the machine starts dropping down when you clam it open ) it will close to far down, if the blue release lever to open the clam feels easy to move, the machine is closed to far, you should feel resistance on that lever.
hope it inspires you to find your fault.
Linear Mode
