I recently took out some Lionel stuff, and set it up on the living room rug. I tried to run 2 powered Lionel SD9s, but they wouldn't run as a pair. Singly, they'd do fine. However, when put back-to-back, they'd pull in opposite directions, and seem to short out. (???) Put in line, they'd go about 1/2 an inch, then quit. I don't know much at all about 3 rail, or AC power. Is there some way that these guys can run together, or can only one go at a time? Is my cheapie powerpack just not powerful enough? Would I have to reverse wire one to run it backward with another? Grasping for straws here...any help greatly appreciated.