The Dumont RA-103 is one of my favorite vintage TVs. Well engineered! Here are some restoration notes on my Meadowbrook:
http://antiqueradio.org/DuMontRA-103Television.htm
That's an "original recipe" RA-103. Your RA-103D is in the Rumson cabinet:
http://www.radiomuseum.org/r/dumont_...n_ra_103d.html
I think the "D" model has a couple of different tubes & sundry other changes, but isn't radically unlike the RA-103. Download the Sams manual here:
http://www.earlytelevision.org/tv_sc...ams_b-c-d.html
As for weak spots, you won't find many. The focus pot is troublesome on some early DuMonts. The tuner mechanism is a little complicated, but the tuners are usually fine after you remove the old petrified grease and clean/relube everything. If the tuner feels stiff when you get your set,
don't force it!
Regards,
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html