Just posting this in case someone runs into the same issue. Placed new FP-45 number 22401 on track and the engine would go forward about one foot and backward about one foot and then barely move. Noticed that the rear motor was spinning the wheels but the front motor was doing nothing. Pulled off shell and manually turned front motor flywheel a few revolutions and then it would bind, same thing going the other direction. Removed truck assembly from motor and the truck wheels would do the same thing, partially turn one direction and bind and then bind again going other direction. Eventually discovered the small idler wheel, maybe wrong term, on the outside of truck had something stuck in it's teeth. I believe what happened is during manufacture they attach the end pieces to the body with what looks like hot glue, well a drop of it hit this gear and hardened. Glad I figured it out and didnt have to deal with returning the engine.
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