Good morning,
this loco stops randomly. It goes forward, I reverse the direction of travel, the lights switch but the loco doesn't move I have to tap it on the roof to get it moving.

The decoder is the one that does not need a permanent magnet

I oiled the rotor axle, I oiled the wheels, checked that the cables are soldered properly, checked the rotor to see if it is dirty, checked the brushes all seems in order.

What else could I do ?

The engine is quite old, the gears do not have any symptoms of being worn out either, they move freely without getting stuck in any position.

Ideas ?

Was thinking of buying a retrofit kit and see if it improves things or not.

Thank you