Back over 4 years ago when I started making wagon kits I wasn’t aware of the Parkside (Now Peco) PA34 mounting blocks. I made up both a plate and trestle wagon,. On these I made up from plasticard a mounting that would accept the dovetail on standard Bachmann narrow tension-lock couplings. The trouble was that I didn’t get a good enough ride height, and lost the flexibility found in the NEM pockets. The result was unreliable running with frequent derailments, something I have since learnt how to avoid by careful modification of the PA34 mountings.
Last evening I decided to cut away the old home made fittings and replace with my now reliable versions. Here in a train that has only 2 RTR items, all the rest kit made. and behaving well. One trestle wagon is missing as the chassis is not flat, distorted over years of heat soaking in the loft. I have now fixed the derailing problem by changing the wheel sets for Hornby that have a somewhat deeper flange, just enough to cure the problem.