What would cause a train to run better backward than forward? If it can go one direction it should be able to go the other just as easily, right?
When a train runs better backward than forward, that’s an indication of uneven wear. That doesn’t necessarily mean it’s an expensive repair though.
Why it’s not unusual for a train to run better backward
When you find a vintage Lionel, Marx, American Flyer, or similar electric train, it’s not super unusual for it to run better in one direction than the other. After all, it probably spent 98% of its time running forward. That means the brushes wore in the forward direction, and the electrical contacts that go forward withstood more arcing than the ones that go backward.
But there are some inexpensive fixes you can try to get the train running well in both directions again.
Clean the reverse unit
The most common reason for directional problems is dirty or worn contacts in the reverse unit. Sometimes you have to rebuild it, but you can try cleaning it first. The reverse unit is the assembly directly in front of or behind the motor, frequently covered with kraft paper. Spray some contact cleaner (not WD-40 penetrating oil, in spite of what that guy on Youtube says) into the unit, shake the engine up and down, and let the cleaner run out and dry. Give it a good 30 minutes to dry.
You can buy actual contact cleaner in the electrical aisle of a hardware or home improvement store. A can costs around $7 and lasts a long time. It’s really good for cleaning the wheels on the engine too. I use the CRC QD brand, but they all have the same active ingredient in them.
After the reverse unit has had a chance to dry, try running it again on the track.
Replace the brushes
The motors in vintage electric trains have replaceable carbon brushes in them. These brushes wear out, but they’re designed that way so the more expensive parts in the motor don’t wear out. Vintage Lionel service manuals told their dealers to replace the brushes any time a train came in for any service. It was an upsell for certain, but it did help keep the train running well.
Every brand of motor is a little bit different, but the brushes are generally held in their wells by small brass or copper springs. Pop the spring back with a small screwdriver and tilt the motor, and the brush usually drops out. If the brush is really short or worn at an angle, it needs to be replaced. If the side that contacts the motor is relatively square to its sides, the brush is OK and you can put it back in.
Replacement brushes are pretty widely available on Ebay. They aren’t all interchangeable so be sure to at least buy the right brand. American Flyer, Lionel, and Marx are all widely available. The listings will usually tell you what motors they fit. Flyer brushes tend to be more expensive than Lionel or Marx, but in any case, we’re talking parts that cost a few dollars and take less than 15 minutes to swap out.
Rebuild or replace the reverse unit
If neither of those things help, it’s probably time to rebuild or replace the reverse unit. Marx reverse units are pretty easy to rebuild. Lionel and Flyer e-units are a bit more finicky. I’ve had better luck replacing them. Buy a rebuilt Lionel or Flyer unit on Ebay, then wire it in the same way as the old one was. A rebuilt 3-position e-unit should cost around $20-$25.