Don't crank that inductuner mechanism too hard until you have a chance to pull the chassis and give it a careful cleaning & inspection. This article has some photos of the tuner:
http://antiqueradio.org/DuMontRA-103Television.htm
I've heard of those tuners having a broken ceramic shaft. My RA-113 even had a broken gear in the mechanism. Those things might have happened when lubricant dried up and turned hard, and then someone forced the tuner.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html