Walthers Grill Diner

I recently recieved a walthers heritage grill diner in phase IV scheme I tried running it on my layout behind a pair of viewliners and trailing 2 express boxcars and an amfleet 1 coach yet when the diner car went around the first curve it decoupled i then noticed that the coupler of the diner car was about a third of a centimeter too high I don't know why it's higher than the others seeing how their both walthers cars. Yet the diner cars coupler fits with the amfleet 1 coach By bachmann perfectly it also fits a bachmann Full dome car I would apericiate any advice or feedback

Thanks

I really need some feed back on the solution

Yeah, I know what you're talking about

What I generally do is bend the couplers but before doing that I take washers Kadee #209 and place them in the boxes so that there is little vertical play and if the couplers are still too high/low, then I bend them down/up respectively.

That has worked for me and hopefully you will have the same success as well.