2 solutions for you. 1 take off the uncoupling tab armature. Remove the screw and spring. Take the spring and stretch it out just a tiny bit. Do not over stretch it. Then reassemble every thing as it was and tighten the screw back down. That may help.
2 if you do not care to ever uncouple the cars or at least keep them together in a unit train consists. Just use plastic zip ties to keep them from commimg open. If you find two cars with trucks that do not give you problems coming uncoupled. Put them at either end and then zip tie all other cars in the middle. This way you can keep them all together as a unit, but still be able to uncouple them from either end by hand or with an uncoupling track section.
