Hi George, lots of questions. Since I am on cell phone I will make this brief. More later if you want it.
1). 1946. Horizontal e unit and smoke bulb tell for sure.
2). No balls in the bearings. Since this is a spur gear drive motor there is little axial thrust, so no thrust bearings needed. In ‘46 Lionel was thinking, incorrectly, that the oilite bearings would never need lubrication. So they made little provisions to oil them. Later versions of that motor have a hole drilled between the bearings to add oil. You may want to drill that hole as it makes life much easier. If you are interested I can send photos later.
3). End play on that motor is not a issue as long as commutator doesn’t not hit brush plate. Again, no axial thrust as no worm gear.
4) spur gear would be removed from armature shaft with proper size gear puller. I would recommend against this as I believe it will be difficult to reinstall without damaging the commutator.
6). Normal wheel spacing on most post war locos is axle flush with wheel hub on both ends. When I get home I will check if I have recorded Wheel gauge at Intersection of flange and tread.
Lionel never produced a service manual for the ‘46 turbine, there is a parts list.
Replacing an axle worm wheel on this engine is uncharted territory. There were only two locomotives built like this one. They are the ‘46 turbine and the ‘46 Berkshire. The worm wheels and the side rods are parallel drive linkages. Everything after these two locos used a single worm wheel and drives with the side rods. The question I have never been able to find anybody to answer is how close do the worm wheel teeth have to be in alignment with the side rod holes to get the front and rear driving axles to work together? You could just remove one of the worm wheels and you would have a drive train almost like ‘47 and later turbines and Berkshires. Or you could change the bad worm wheel and teach the rest of us how it is done.