MTH S guage coupler issues.

I have purchased two of the MTH S gauge reefers and I had a problem with them not staying coupled.  What I noticed is that the coupler drops down so that it is not parallel to the track.  The coupler would become uncoupled even though the coupler didn’t actually open.  When I took off the truck I noticed that the hole in the coupler shaft is larger than the hole in the truck.  I solved the problem by using super glue to attach the coupler shaft to the truck so that it is now parallel to the track.  It concerns me that if I want to convert to scale couplers that I may not be able to get the coupler off the truck.  I’m hoping someone has a suggestion for a less permanent solution. 

On the old SHS coupler, the hole on the coupler shaft was also larger than the hole in the truck.  The larger hole fit over a slightly raised boss on the car's bolster:

Here it is after fitting it to a Lionel/Flyer Hopper using American Models trucks.  No glue, super or otherwise was used.  The only thing holding everything together is the truck screw:

I don't have an MTH hirail car to compare against, so I can't study how the coupler might have cause to flop around.  But, there are super glue debonders available that will enable you to remove the coupler from the truck at a later date if so desired.

Rusty

Thanks for the information.  If the next car I buy has the same issue I will trim off the screw mount.  John.