What is the difference between the Bachmann Bumble Bees 83195 engine #345; 91602 engine # 178, and engine # 177??? Thanks

Loco Bill:  Just read your article on replacing the Axle Drive gears.  I just tried to run a Spectrum 2-6-0 Mogul which I bought several years ago.  I put up a ceiling track
and am now ready to run trains.  Unfortunately, the 2-6-0 just hummed and sounded like it was slipping gears.  I had previously completed the lubrication instructions
since it is a new engine.  Turning the engine over, I noticed when I hand rolled the wheels that there was no apparent movement of the "white" gears that I could see.
Could it possibly be that axle gear?  Or is there something else I can try?  I do not want to over oil it so I haven't tried to put more oil in the box.  Any suggestions???
Thanks so much for any help in this matter.

I have a 2-6-0 Mogul Steam Locomotive, do I need to use a sensor magnet on the engine?  Where would you put it.  I bought a LGB 1705.

I have a new Loco 1:20.3 and I have purchased 322 track.  Will this work well.