When I receive a new modern engine, I do a lot of the tests posted above. But being new, they are expected to work. Lately, though, I've gotten back into a lot of Postwar Lionel purchases and my routine for these "new" engines is quite different. I really enjoy the challenge of getting these vintage engines running to my liking. So.....
1. I've already checked the photos of the engine to see what parts I might need for an initial parts order (as well as the usual brushes and springs,pickup rollers). I like to have them the day the engine arrives
2. Unpack it and see if anything has changed since the photos (externally)
3. Put it on the track with no lube or adjustment and power up (just to see what I'm facing mechanically)
4. Take the shell off and wash it with dish soap and a soft toothbrush and possibly polish
5. Remove the trucks and soak them in mineral spirits and then alcohol to loosen old lube and dirt, clean them out, brass wheel Dremel the wheels and then relube. Rewire, if necessary, the power wires from the rollers and the sliding shoe wire.
6. Move on to the e-unit....clean it with contact cleaner and hit the plunger with contact cleaner/lube
7. Remove the motor/motors. Open the brush plate, clean the commutator, lube the bearings, replace the brushes and if necessary, rewire the motor(s).
8. Put it up on my rollers and test the motor(s) and e-unit for proper operation.
9. Move on to the horn (which could take longer than any of the above). Clean and adjust relay and solder on jumper wires to shorten the conductivity path for these finicky horns. Adjust the screw to "taste" (assuming it works).
10. Put the chassis on my layout and run it through it's paces. This step to me is the most enjoyable part of it. If all that works, the shell goes back on, a consist goes behind and I'll sit back and watch it.
With new modern engines, the testing is basically step 2 and 3. If those engines don't work properly at that point, I'll fix what I can or......send it back.
Roger