I have two 742 engines, one has a spring loaded arm on the frame in the center in front of the wheels. It looks like it was intended to hit something in the center of the track and move what looks like a paddle forward to where the headlight would have been if it was a powered 1950 engine. The other 742 does not have this lever. Any ideas?
Yes. Originally it came with a sparking feature. The arm held a what is basically a zippo lighter looking flint, which would hit on a spinning stone wheel, that is powered by the mechanism.
The arm just flops around and hits it periodically causing a spark to shoot up and out of the smokestack. It is not spring loaded or anything. I believe these probably wore out pretty fast and Im just guessing many people simply removed it rather than replacing the flint.
Pictures attached of my loco with this all still in place.