If you have a Lionel electric train whose lights flicker and (possibly) runs erratically, I have an easy fix.
I’ve owned at least two locomotives–a modern-era Lionel diesel and an American Flyer model 3110 steeple-cab electric made in 1929–that exhibited this problem. They ran fine for at least a couple of laps around the track, but came to a sudden stop after they had been running for a few minutes.
The usual solution to this problem is cleaning the wheels and the pickup rollers. That should always be the first step. Grab a package of cotton swabs and a bottle of rubbing alcohol, or better yet, mineral spirits or contact cleaner. Dip a swab in the cleaner and swab down the wheel until the swab is filthy. Flip the swab over and repeat, replacing swabs as necessary, until the wheel or roller can pass a white-glove test. Clean all the wheels and pickup rollers this way. Dirt inhibits conductivity, and the arcing that results from it just makes matters worse, attracting more dirt and eventually it causes pitting in the surface.
That’s usually enough, but there’s another step you should go ahead and do because it’s going to need it at some point anyway.
Next, get rid of whatever dried-out lubricants and other foreign matter that might be on the axles of the pickup roller. Spray a little contact cleaner onto the axle, then turn the locomotive right side up so the cleaner can drip out, along with whatever gunk it dissolved. Let it sit that way for about 15 minutes.
If all you have is oil, apply one drop of oil to each end of the axle on each pickup roller. Better yet, apply a drop of Rail-Zip or Deoxit to each end of each pickup roller axle, turn the roller with your hand to make sure it rotates freely, then let it sit, preferably overnight, and let it work. Both Deoxit and Rail-Zip work chemically more so than mechanically. After about 12 hours, apply a drop of lubricating oil.
After this treatment, it will run much more smoothly and have a much longer life expectancy. The poor conductivity that causes the arcing also causes excessive heat. Motors can tolerate some degree of heat of course, but too much heat can cause damage to the windings on the motor’s armature, a costly repair that not all repair shops can handle themselves.
Regarding Deoxit and Rail-Zip, I don’t have the ability to evaluate them chemically, but they behave similarly and look and smell the same to me. I use them interchangeably. And I’ve used a fair amount of both over the past decade.
The same treatment also helps passenger cars and cabooses that have lights in them to work better, though the way some cars are designed, it’s sometimes impossible to eliminate flicker completely without modifying the car.