Sal9000,
I did the amp draw test as you suggested on my 1950 773. I got 3.15amps. When I bought this engine 6 months ago, I performed the "Super Tune" procedure as described on the JustTrains website. It runs smooth and strong, but according to your figure, I'm pulling too many amps. I checked the armature shaft/worm gear shaft and that appears to be straight and the armature turns easily with one finger. I checked the back and forth play and there is some, but I don't think it's excessive (I could be wrong about that). The JT article describes normal as being the width of a thrust washer. I think that's about what it is, but I'd have to open the worm gear compartment and slip a thrust washer in there, I guess. What would account for the large difference in amp draw between mine and yours?
Roger
Well, to be fair, I only own one 1950 issue 773 and that's what she does so I'm not sure if I'm the expert . And actually, as I was typing this I thought of something. That 1.5 A figure was done on a small chunk of non-ferrous track with short transformer leads. I just tested it on my largest run (~45 feet, with ~15' transformer leads) which is ferrous and I'm getting ~1.9-2.0 A unloaded (no tender even) at slow (creep) speed (more conductor length and MagneTraction will eat some current).
That much current would alarm me. I've seen "official" docs that state the current rating for the Pullmor is 2.5 A (can't find it now of course), and I've warped field bobbins on a postwar Trainmaster I was tinkering with (traction tires, additional weight) after letting it run at ~6.5 A (~3.25 A/motor) for ~30 minutes.
Try measuring current on the motor running uncoupled from the drive train. I just tested a Pullmor unloaded at low speed (not from the 773 though) and was getting ~0.7 A. The unloaded test will tell you where to focus - if it's less than say 1 A there's something up with the drive train. If it's much higher than say 1 A, something is up with the motor (Old brushes? Old high resistance wiring inside the locomotive? Wiring mistake?). The meter could be askew too - probably a long shot but how about a second current measurement method (my measurements above I used both a current clamp and then a Fluke 177 - they are within 0.1-0.2 A of each other)