Jerky Life Like GP18

[Biased turkey]

I cleaned the track, I cleaned the wheels and the GP18 is still running very jerky.
On the other hand my Life Like SW9 runs very nicely so I suspect a faulty GP18.
I removed the shell, and put it onthe track again, but the problem is still there.
If I press slightly on the top of the chassis it runs a few inches than stops as soon as I release the pressure.
I then took a tweezer and move a little the 2 long contact strips running along each side of the chassis ( are they made out of brass ? ). I didn't bend them , just moved them a little toward the inside.Then the loco runs a lot better for at least 2 hours. I tried it again this morning and it still runs fine .What should I do to fix that problem permanently ?
See the pic. It's not the pic of my loco ( I didn't take it apart , just removed the shell )
Just to show the part I moved slightly.
Is there any way to clean that contact ?
The Life Like assembly instruction sheet doesn't mentions anything about cleaning those 2 contacts.
tia for any suggestion.
B.T.

 

[umtrr-author]

It's possible that you did fix the problem permanently. Maybe the contacts somehow became unseated or misaligned in some way.

 

[Biased turkey]

I didn't fix the problem permanently, bacause yesterday night the problem hapened again.
I cleaned the track with a brightboy, cleaned the loco wheels ( feeding 1 truck with DC voltage and spinning the other one on top of a paper towel with alcoohol )
I noticed that the wheels on the rear truck are spinning smoothly if I lift the front truck slightly off the track.
Obviously, the problem is not a wheel problem but a contact problem.
I took the loco apart ( now , it really looks like the one on the picture )
I swaped the front and rear truck, but the problem persists.
Tonight, I'll swap the strip contacts ( see the red arrow on the pic ) , spray some contact cleaner on them and slightly bend them downward.

I hope it'll work because if it doesn't I don't know what to do next.

 

[Biased turkey]

It didn't work, so I went a step further.
I removed both truck and took it apart.I cleaned the wheels and the current pick-up ( see blue arrow ). Then I bent the pick-up slighthly to have a better contact, put everything back together, greased the gears and voila...
My GP18 run as if it was brand new.
As an electronic technician, I'm amazed with N scale because there are so many small contacts points to bring the current from the rails to the motor:
1) between the rail and the wheel
2)between the wheel and the truck pick-up ( blue arrow )
3) between the truck pick-up and the long flat strip contact ( red arrow )
4) between the long flat strip contact and the frame
5) between the frame and the brushes

That was a good experience.

 

[Biased turkey]

Now my GP 18 is running as smooooooth as a Molson beer.