Scale Trains first gen turbine derailing

[propmeup1]

I have a first gen turbine #51. I've had it since they first hit the streets. Now suddenly the first axel decides it wants to derail only at certain areas. It ran fine for as long as I've had it till now.     I run it fwd and rev several times at two of these areas. It looks as if it comes off at just a slightly lower spot on the rail head. I built up two places with solder and file it flat and that seems to work.

Just wondering is there another fix to help this issue. I have no other locos doing that and I have many with no issue. Even the ST Big Blow runs fine.

Thank you in advance.

Keith

[Englewood]

I wonder if the wheels on that axle have become out of gauge?
Good job on the rail repair. I've seen the same concept used on the real thing.

[C855B]

Be sure to check if there's not something interfering with the motion of the front idler truck, the non-geared second truck. It's spring-loaded to exert enough pressure for electrical contact. If there's something restricting or limiting its vertical flex action, it could be pressing down on the back of the front truck and lifting the front axle.

[propmeup1]

I'll fool around with it a bit more. I did check the wheel spacing and that was alright. I'll continue to look it over.  Glad you like the solder trick.
Thanks.