Observations - Prairie Shadows 3800 n scale hoppers

[Narlie]

Have these cars since Sept 2022. All seemed well at beginning. Now noticing some units make a binding sound. At first thought it was my loco. After a close look noticed a ware mark on some axels where the coupler box screw is.
Obervations - coupler box has partially open sides ( advertised as micro trains ?). Truck is secured with a bolster pin not a screw as is the custom with Rapido/Prairie Shadows cars. Truck is not snug on car as pin sticks out below car. Could be a source of derailments. Pin appears to be of small diameter, not sure an MT equivalent is available.

Actions: Have tried to tighten down coupler box screws. so so results. Tried using MT 209 washer but this changes coupler height.   
Will continue to work on these cars.
Has anyone else seen this problem?

[bbussey]

So ... the problem is that the axle is rubbing against the coupler box screw?

If the screw head is not flat, you could change to a flat head screw and chamfer the hole.  If it already is a flat head, you could deepen the chamfer on the hole and try to set the screw further in.

[ljudice]

Looked at mine - no interference, rolls freely...