I've been wanting one of these for some time. Last year i purchased a used one from an Ebay seller. Long story short, he refunded almost all of my money when I could not get the accessory to operate. I tore it apart and tried to find the problem with no luck. There is a gearbox in there that's quite interesting, to say the least.
Fast forward to now. Again, from a different Ebay seller, I purchased a new in the box reactor. This evening I had the time to open the box, cut the tape on the styrofoam packing and hook it up. Lights work, chute works to dump spent fuel. But the arm, which depends on that gearbox does not move. Yes, I have the selector lever in the automatic position. The arm moves about a half inch and stops. I can hear the motor running, but the arm will move no further.
A stop at a local service station is next, because there is no way I'm opening up this baby. I did contemplate sending it to Lionel but I don't relish the thought of paying postage on a box this size.