Slipping gears on Railking GP7

Sounds like the screw holding the motor to the truck is loose. It's on the underside of the frame near the center of the truck.

John H posted:

Sounds like the screw holding the motor to the truck is loose. It's on the underside of the frame near the center of the truck.

Is it the black screw closest to the fuel tank? If so, then that screw wasn’t loose. Also, I should mention that the wheels can freely rotate. Is this bad? Only the front truck is having this problem.

The circled screw is on a Premier GP38 truck and it is near the fuel tank. The wheels shouldn't turn. If the screw is tight remove the shell and make sure the motor is actually tight also. If it is also tight, I would take the screw out and examine the motor gear. But working in only one direction sure sounds like a loose screw. One way the worm gear pulls itself into place, and the other direction it will push itself off the gear.

Hi John,

I took the shell off and can confirm that the front motor is indeed loose. I can actually lift it up, but not remove it, while the rear motor appears to be fine. Also, the motor mount screw is tight, so I do not understand why the motor isn’t secure. Any thoughts as to what could be wrong?

EDIT: I ran it with the shell removed, and the motor wobbles when running, but only in one direction.

Depending on how far you want to go, I would remove the screw and compare it to the other motor screw. It could be that the screw is too long. If you have had this since new, then that's not likely. Without seeing it, I'm afraid I have no more suggestions.

John H posted:

Depending on how far you want to go, I would remove the screw and compare it to the other motor screw. It could be that the screw is too long. If you have had this since new, then that's not likely. Without seeing it, I'm afraid I have no more suggestions.

I have had this engine since Friday, so it is new. In fact, this is the second GP7 I have, because the first one had to be returned, due to a missing lens. Counting my 4-6-0, this will be the third engine that has had problems shortly after opening the box. Regarding the GP7, I do not feel comfortable messing with anything, as I had issues with one of my other MTH engines recently.

Could be the screw is a little cross threaded in the motor, remove the screw, clean the threads a little if needed and carefully reinstall correctly into motor. This happened to one of mine and thats how the MTH tech fixed it. The threads should not be damaged, because at the factory, the tool used for installation only tightens to a preset torque.  

I'm with you on not messing with a new engine. But, one more question; when you move the motor does the screwhead also move around?

John H posted:

I'm with you on not messing with a new engine. But, one more question; when you move the motor does the screwhead also move around?

I’ll have to take the shell off again to check. Quick question: What would it mean, if the screw does move around? Am I going to have to send another engine back? I honestly am at wit’s end.

The motor can come loose from the collar that mounts to the truck. If you remove the screw circled in the earlier picture, pull the motor and collar from the truck, you can tighten the screws that secure the collar to the motor. I usually coat the threads with clear fingernail polish to make sure they do not come loose again.

It’s fixed! It is now running as it should. Thanks guys!