jardeon

This is going to sound a little silly, but I've noticed this in older sets (Emerald Night, Maersk Train) and it seems that what's happening is the small magnets are moving around in the plastic housing. If you join together the two magnets and notice that they are weak, simply shift the magnets against each other vertically... grab one carriage and slide it upwards against the connection while sliding the other downwards. You should be rewarded with a very satisfying CLUNK sound, and you'll notice that the magnets are much more strongly engaged.